School curriculum: what is n in physics? Art nude model from Kazakhstan: "Shooting nude does not mean sleeping with a photographer."

Nude photography has a long history as a provocative art form. The human body is a beautiful creation in itself, whose intricate shapes, smooth contours and unique features make it a stunning photographic subject. However, the photographer needs to be careful about how, while maintaining a professional approach to business, to get the intended aesthetic presentation on their shots. Always plan ahead for your photo shoot, use a wide variety of photography techniques to capture the beauty of your attracted model, and make sure she feels comfortable at every step of the process.

Steps

Part 1

Find a model ready to go nude. Your first priority is to find someone who will agree to nude photography. Try to communicate with women who are fond of modeling and are interested in photography as an art. If you do not have such contacts, you may be able to hire a model through a professional modeling agency. Before using the services of such agencies, make sure that you are able to pay for them.

Have an idea of ​​what you want to achieve. Before you light up the idea to start photographing as soon as possible, you need to clearly mentally imagine your idea and how to implement it. Consider what kinds of thematic elements you can use, as well as consider technical considerations, including possible camera angles, ideas for lighting, and choice of shots. The worst thing you can do is start nude photography without preparation. There must be an invisible atmosphere of trust between the fashion model and the photographer, and if a girl has to undress in front of an unprepared amateur photographer who does not even have any idea in her head, it will not be easy for her.

Find a suitable location for photography. Pay attention to eye-catching places that can be good for nude shots. The visual intrigue of the chosen location should do justice to the beauty of your model. Natural landscapes, including fields, forests, and bodies of water, are popular choices as they complement the nature of the naked body. However, as a background, you can also choose industrial sites, urban buildings and any other interesting places.

• Avoid public areas and places where you will be watched or disturbed.
• If you need permission to take photos in a particular location, please arrange all formalities before you start shooting.

1. Set a time and place for a pre-meeting. Make an appointment with the model to discuss the details of the shoot with her. Invite her out for lunch, coffee, or visit your studio for a friendly conversation. Try to break the ice between you before you get to work. When it's time to uncover your camera, you'll already be familiar enough to be able to communicate with each other more comfortably.

   • Be sure to outline your concept so that the model has an idea of ​​what to expect. Don't be afraid to ask the model about her attitude towards what you have in mind.
   • Use this time to assess the model's comfort level with regard to the idea of ​​future photo shoots. Go to the main one and initiate a dialogue with questions: "Would you mind if ...? How would you feel about ...?"
   • A preliminary meeting is not a date. Do your best to help the model relax, but maintain a proper professional attitude towards her.

Part 2

1. Pay special attention to setting the lighting. Distribute the light sources so that they illuminate and accentuate the natural forms of the model. If you're shooting in the field, it could be the soft diffused light of a sunset, or it could be a more pronounced balance of light and shadow for contrasting black and white photos. Your lighting should be in harmony with the shape and pose of the model so that you can get the most aesthetically pleasing photographs.

   Experiment with different photography techniques. Until your photos become known for their own distinctive style, don't be afraid to experiment with different compositions, filters, lighting, and so on. Each of your models will be unique, so each of your photos should be somewhat different from the rest. Be thoughtful and take the time to capture all the nuances of your subject, location, lighting, and action.

   • Mix different techniques. For example, include a few black and white photos in a series of rich color shots, or find other ways to include various thematic elements in your photography.
   • Consider what can be done to improve appearance of your photos (without changing them too much) while editing.

2. Don't be afraid to be spontaneous. You don't have to be too strict about pre-set plans. Although it is important to have certain ideas in mind, improvisation can give you fresh and exciting footage. Sometimes best ideas are born by accident when you are just fooling around. Who knows, you might make a breakthrough if you just let things take their course.

   • Instead of sticking strictly to a sequence of predetermined poses, let the model move and pose freely while you photograph everything you can. If there is nothing worthwhile in the frames, then you can easily delete them, but you may end up with one or two truly special photos.

3. Don't feel like your photos have to be very revealing. Excite lifeless shots with a selection of clever ways to hide or play with the charms of the subject. Use minimalistic accessories (scarves, jewelry) to cover the intimate parts of the body, or shoot the model from an unusual angle or in the process of interacting with furnishings, taking into account the spatial perspective. The goal of nude photography is not always to show the female body in all its details. Sometimes the fewer the better.

Part 3

1. Give the model some privacy. Give the model a private place where she can undress and get ready for the photo shoot. This way she won't have to undress in the field right in front of you and the rest of your team. Any person will feel uncomfortable completely taking off their clothes in the presence of spectators. Remember that the model's comfort is of paramount importance, even if she has been nude hundreds of times before.

   • It's also a good idea to have a bathrobe or other comfortable clothing ready for the model to put on if she gets chilly while you prepare for the next series of photo shoots.
   • Be prepared to clear the set of excess personnel and start working one-on-one with the model if she doesn't like the idea of ​​having a large crowd around.

2. Try not to touch the girl. As a photographer, you must be aware of your intentions and be able to give clear instructions so that the model can realize them. This does not mean that you can treat the model as if it were an inanimate object. Be clear about your instructions on how and what to do, rather than trying to pose the model yourself. Even if there is nothing wrong with your intentions, any touching of a girl when she is completely naked can be misinterpreted.

   • Make it a rule to keep your hands away from the model, unless she herself asks you to help her strike or reproduce a certain pose.
   • The nude model is not a prop. Remember that the woman you are photographing is also a person who has every right not to be touched without permission.

3. Cooperate with the model. Give the model some freedom in how she poses. Encourage her to make her own contribution to your project by showing her personality. It is likely that this will not be her first nude photo shoot, so with her experience and knowledge of her own body, she will have a better idea of ​​\u200b\u200bwhat looks best in photos. Feed off each other's ideas and draw your inspiration from them.

   • Make sure the model agrees to your requests before asking them to comply.
   • Working with a model that knows how to help you make your vision a reality can be a very rewarding experience for you.

4. Conduct yourself professionally. Your interest in nude photography should be solely due to the fact that you see beauty, mystery and great expressiveness in the naked human body. Take the model seriously, perceive it as an experienced master of their craft with their own considerations. Never make jokes about her body, do not make ambiguous or judgmental remarks. If you offend the model, she will begin to have a negative attitude towards working with you.

   • If you seriously upset the model, she may be openly critical of your talents and advise others to also refuse to work with you.

• Try to make sure that the process of photographing is fun and good-natured. This will help build confidence, uplift the spirit and create a more pleasant atmosphere for communication.
• Prepare a playlist of your model's favorite music to make her feel more relaxed and confident during the photo shoot.
• Ask the model to come to the photo shoot in loose clothes. This will avoid unsightly marks on the body from tight outfits.
• When you're done taking a photo, use the photo editor to improve the look of your photos, as well as fix obvious imperfections in your photos.
• Ask the model to lubricate the skin with a thin layer of oil. Light shine will emphasize the contours of the body and help to achieve the maximum result from the supplied lighting.

Warnings

• Ask the model for her opinion on editing her body features in photos. Some models are more tolerant than others.
• Be sure to ask the model for permission to touch her or start filming her in a new pose.
• Before submitting photos, make sure that the model has nothing against other people seeing her photos.
• Do not do anything to overly sexually arouse the model during or outside of the photo shoot.

The nude theme has been popular since ancient times, even before the invention of photography. At all times, the beauty of the naked body was admired. Here we take a look at female nude photography and give you tips from experts to help you get started in nude art. Plus you get a free posing guide.

Start: Finding a Model

Perhaps the biggest problem is to find a model who is ready to shoot nude. If you're lucky, it could be one of your acquaintances, but this rarely happens. Most The best way- Look for local models on well-known sites such as http://www.modelmayhem.com/ , http://www.purestorm.com/ and http://www.onemodelplace.com/ . These sites are a meeting place for photographers and models. You will usually be able to find a local model willing to be filmed on TFP terms.

If you go down this path, you need to clearly state what is expected of both parties, especially if there is no financial commitment. Experienced models will most likely not agree to work on the terms of TFP, however, if you want to make a good portfolio, it is worth considering investing some money in it. It's not so much about finding models who enjoy being nude, but about finding correct type figures for artistic shooting nude. You need to carefully study the portfolio of the model before inviting her to shoot. There is a noticeable difference between models who shoot primarily in the glamor genre and in the nude genre.

Choosing a shooting studio

You don't need a huge studio to take good nude photos, but you still need to have enough space to position a couple of lights and a background, as well as to stand back enough to shoot the whole model without using a wide-angle lens. The medium-sized living room practically meets the minimum requirements. We rented one of the studios in Reading for the day. There are many studios in the UK that offer this kind of service. Many also offer a one-day nude photography course and will find a model for you. Prices and conditions vary, but on average be prepared to pay £50 an hour for a studio and model. If you are on a budget, you can share the cost with one of your colleagues or friends who would like to join you.

Lighting for nude photography

Studio lighting can seem very complicated to the uninitiated, but now that you can view the image and histogram on the camera screen, everything is much easier. The lighting tips below are a good starting point, giving you three basic patterns for setting up your light. If you're new to the studio, start with simple circuits - you'll be surprised at how creative you can use one light source and reflector. Once you're comfortable with one source, move on to more complex options like high and low key.

If you don't have your own lighting kit, there are places where you can rent one. For example, at http://www.theflashcentre.com/ you can grab a two-source Elinchrom 300RX weekend set for just £14.

However, studio lighting is optional. Daylight from a window, ideally facing north, makes for great photos. Even using a regular on-camera flash can be a good alternative.

It is better to use, if possible, simpler lighting schemes. You don't want to miss out on interesting shooting moments by constantly adjusting the light, do you? Before the model arrives, you can try out your lighting ideas on a dressed assistant, then you will be completely ready to shoot and do not waste time. Try not to worry and stay calm while shooting.

Basic Nude Lighting Scheme

This scheme is a good starting point for artistic nude photography. Two light sources are directed at the model at an angle of approximately 45 degrees. It is better to place the main light a little higher than the model. Its power must be greater. The second source is filling, its intensity should be less and it should be placed lower. If you only have one light source, use a regular reflector.

High Key Lighting

To create a soft, even light, place two softboxes directly in front of the model. One should shine from above, its power is higher. The other softbox is located at the bottom and has a slightly lower power (shell scheme). Use two additional sources to light the background so that it becomes pure white. To separate the model from the background, use two large black panels on the sides. This will create a slight darkening along the contour.

Low Key Lighting

Basic studio equipment

There are many starter kits that you can buy online. For example, the excellent Apollo Pro Line 300. Usually the following equipment is included in the kit:

Studio flashes have controls on the back. You can control the power of the pulsed and pilot light. The modeling light allows you to evaluate the light pattern on the model while setting up the circuit.

An umbrella is included as standard in most kits. It happens with a silver, golden and white coating, for reflection and for transmission. Easily attached to the flash.

softbox

The softbox is also attached to the flash and gives a soft, diffused light. There are different forms and sizes. Gives more controlled light than an umbrella.

Racks have great importance. Flashes are attached to them. Racks are telescopic, which allows you to adjust the height of the source. To improve the stability of the stand when using heavy flashes and attachments, use a counterweight.

Nude art is often shot in monochrome, so simple black, white, or gray paper backdrops can be used. To get a deep black background, it is best to use natural black velvet.

Lenses and camera settings

For these shots, we used three lenses for the Nikon D700 full-frame camera. These are Nikon AF-S 24-120mm f/4G ED VR, Nikon AF-S 85mm f/1.4 G, and Nikon 60mm f/2.8 Macro. The wide end of the 24-120 was fine for full length shots, and the macro lens did a great job of close-ups. But our favorite lens is the 85mm f/1.4. The excellent quality of the optics makes it ideal for this type of shooting.

When you are working in a flash studio, use the M mode.

For most of the photos we used f/8 and a shutter speed of 1/200 sec. As a rule, at this aperture, lenses have the best sharpness. Obviously flash exposure is created by the combination of flash output and aperture. To cut off the influence of external constant lighting in the studio, you need to use a fast shutter speed, as a rule, no longer than 1/100 second. But don't exceed the sync speed.

A tripod is not needed for studio shooting, as a very short flash pulse is guaranteed to “freeze” the object. Therefore, you can move freely and take pictures from different angles.

Your first nude shoot

The studio is chosen, the model is found, now it's time to create.

If you're renting a studio and paying a model for every hour of work, you don't want to spend time thinking about what to do next. Besides ruining the creative process, it looks unprofessional. So make a plan ahead of time. It doesn't matter that you can deviate from it during the shooting process, as long as it is there. Work rationally. For example, if you planned to take pictures with three schemes on a black background and two on white ones, do so in order to change the background only once.

There is nothing worse than spending time in post-processing removing various defects. The most unpleasant from this point of view are traces of rubber bands underwear. They disappear after quite a long time, so it is better if your model comes to the shooting in loose clothes without underwear. Experienced models do just that. It is better if, upon arrival, the model immediately takes off her clothes and puts on a soft bathrobe so that possible traces of clothes are guaranteed to disappear. Make sure. that the model feels comfortable when shooting.

As with all genres of photography, good composition is an essential element of a good nude shot. The same general rules, such as the rule of thirds, can be applied to nude photography as well. This creates a visual sense of harmony in the frame. Look at the beautiful forms that are created with the naked body and light. Don't be afraid to deviate from the rules when necessary, if it improves the photo, you don't need to take the advice as dogma.

As you frame your shot in the viewfinder, get in the habit of running your eyes around the perimeter of the frame, evaluating the overall framing and pose of the model. The slightest change in angle or camera tilt can make a huge difference in a picture. Don't be afraid to take a lot of photos, moving around and changing the point of view and the pose of the model. Stock up on memory cards, these days they are inexpensive.

Nude photography poses

We invite you to download our free Nude Guide - it has great tips on getting started and basic poses. In order to get the most out of it, you first need to understand a little about the theory of setting the model.

Let's start with the concept of "contrapost". This is a term borrowed from art referring to the human body. Contrapost (from Italian. contrapposto- “opposite”), a technique for depicting a figure in art, in which the position of one part of the body is contrasted with the position of another part. For example, the upper body can be shown in a turn, the lower part frontally, the weight of the body is concentrated on one leg, while the other is free, although not separated from the floor.

If you look at the works of the classics of art, for example, the sculpture David by Michelangelo or modern fashion magazines, we will see contrapost everywhere. Understanding the principles of contraposta is the key to creating a beautiful pose, even if you shoot the model from the waist down to the waist, it is still important to pay attention to the position of the model's legs. This is important, as the position of the legs determines everything else, including the position and posture of the upper body.

Direct eye contact when shooting art nudes is best avoided, as a direct eye is more associated with glamor or beauty. However, this rule can also be broken if a direct look works well for the idea of ​​the picture.

Black and white photographs

Monochrome is often used for art nude photography, as the removal of color information helps to focus on line, shape, and texture. To make it easier for yourself when shooting, if you want to get black and white photos, switch your camera to monochrome mode. So you can not be distracted by color and focus on lighting.

As long as you shoot in RAW, switching your camera to monochrome will not affect your image in any way, you will just see a black and white image on the camera screen. This means that when you download it to your computer, you will see the original color image and, when processed, you can get both monochrome and color versions.

Abstraction and details

Art nude is an art that celebrates the harmony of the forms of the human body. Focusing on certain parts bodies, using natural curves and shapes, you can create interesting abstract shots. To do this, it is good to use one hard light source that clearly draws lines and shadows. For the abstract photo above, we used a 60mm macro lens on our full-frame camera, which allowed us to capture both medium and close-ups. Don't be afraid to drastically frame the image when shooting, such as completely excluding the model's head from the frame. Abstract photography presents us with known shapes, lines and textures in such a way that we do not immediately understand what kind of object is in the picture.

Try High Key Nude Shooting

A good high key shot is not an overexposed image. You have to skillfully show details in the highlights as well, while pushing the tonal range as close to the highlights as possible. In order to make it easier for yourself, navigate by the histogram on the camera screen. Ideally, you should move the histogram as far to the right as possible without clipping in the lightest significant areas ( White background is not a significant area). Turn on your camera's backlight warning when overexposed areas flicker.

To create a high key shot, we used two softboxes in front, one above and one below, and a white background lit by two softboxes. When shooting in high key, there is a risk of losing the model's skin tones at the edges due to reflections from the background. To separate the model from the background, we used black screens on the sides. You need to place them as close to the model as possible, avoiding falling into the frame. The black light absorbers will create a dark outline around the model. By additionally separating the model from the background, they will create additional volume.

Lovely low key

Very often in the art nude, the tonal solution of the image is used in a low key. Using a dark background and side lighting, you can create a beautiful play of light and shadow on the body, which emphasizes the beautiful curves and shapes of the figure.

The ideal material for creating a completely black background in the picture is natural black velvet. Natural velvet absorbs light unlike other materials. If you don't have velvet, you can use a black paper background, but you'll have to carefully control the light to prevent it from reflecting off the paper.

Use understatement

The art of nude photography is quite subtle, quite often the photographer does not reveal all the nudity, but only suggests its presence. This is what distinguishes nude art from glamor photography. The partial concealment of a naked body implies mystery and significance, excites the imagination and forces us to mentally complete the picture. Turning the model's head or looking away or away is a great way to add a sense of mystery. Or the model can look down, as in the photo above. Use the model's limbs to hide some parts of the body.

Get inspired

Browse the works of art nude masters. The most famous of them are Edward Weston, Bill Brandt, Man Ray. Contemporary photographers include John Swannel and Robert Mapplethorpe. Don't limit yourself to photos. You can draw ideas and inspiration from various works of art. Going to an art gallery can be a good incentive.

Model Agreement

If you are going to use photos for various purposes, you need to protect yourself from any misunderstandings. To do this, you need to sign an agreement with the model (model release). Also ask the model to bring her passport to the shoot to make sure she is of legal age. While the copyright to the images always remains with the photographer, it is clear that the model will also want to include them in her portfolio if you are working on TFP terms (in commercial shooting, the photographer is not required to give the photos to the model, he pays her money for this). This is perfectly fair, but it's a good idea to make sure the model signs you as the author of the photos and possibly links to your site.

Okay, you can go. I will think.

…“The audience is over. Everybody's Free". Lowering my shoulders, I trudged along the corridor after the director.

I'll call you back to let you know that your issue has been resolved, - the "real colonel" said goodbye to me somehow too formally before slamming the door of his office in my face.

Well, how did it go? - Pashka asked, not hiding the curiosity flowing from all the cracks.

Oh no, I just waved my hand. And, referring to business, he quickly retreated home.

Lenka, I also did not dedicate the details. Just said it didn't burn out. She sympathized, saying: “Do not be sad, Kotya, everything is ahead of us with you!” I can't stand it when she calls me Kitty...

... Pashka called the next evening.

Well, Konstantin! Cunning same you type! What are you saying to our master? We have never received anyone so quickly.

What? I hurried.

What ... Over the shoulder! You have been hired. In the strip Come check it out tomorrow.

Silent scene...

We didn't get the form. For the sake of such an occasion, I had to buy a black suit, a white shirt and a tie, which I never wore and did not even know how to tie. Lenka did it.

At a strip club, you mean? Nu-nu, - she said with a suspicious frown, tightening a black silk "noose" on my throat.

What does "nu-nu" mean? There are, by the way, very strict rules. And then, you know, they also talk about the work of secretaries in all sorts of different ways. And you haven’t heard any “nu-nu” from me about this yet.

Lenka laughed.

Well, you say! My boss is actually female. So, Kitty, behave yourself.

And Lenka jokingly shook her finger at me in parting.

... As for the strict rules, I did not dissemble one iota. The first thing our shift supervisor warned me about after showing me around the locker room, shower room and my locker was:

Girls do not paw! If anyone, God forbid, complains, they will be expelled immediately. No severance pay.

He also grumbled a little about my hair (I had shoulder-length hair - a tribute to my passion for hard rock, and Lenka really liked it. However, going out on new job, I pulled them into the tail.) - you won’t understand, they say, what kind of men they went, let go of their hair, but then he allowed them to proceed to their duties.

It was our duty to keep order, but at the same time not to shine in the hall. Yes, check back periodically. Well, and if there is noise and screams, then run to the rescue.

I got used to the sight of half-naked (or even completely naked) curvy girls in the very first hours. At first I did not know where to put my eyes, and then this phenomenon began to be perceived as something completely normal and ordinary. In the morning it was even unusual to see dressed girls on the street. In addition, “off the stage” the girls behaved in such a way that they could hardly excite anyone. I remember how on the very first night I ran when I heard screams and abuse near the administrator's room in the hall. A miniature angel-like creature in pink and white lace swore, like a plumber, not even three, but, perhaps, a seven-story mat. I figured out what was wrong pretty quickly. The girl was outraged by the behavior of two clients, who are usually called persons of Caucasian nationality. When the “angel”, having finished the dance, left the stage into the hall, these same “persons” invited her to their booth to dance private. According to the rules, a girl can touch them, but they can’t touch her. They did not want to follow the rules of the "face".

Yes, these black-ass fuckers immediately got into my underpants! - the "angel" was indignant. - I sent them to ***. And this rat - Larka - immediately opened the **** nik: they say, let's dance, it's paid. Yes, she went! Let him substitute his **** if he takes loot from them!

"Larka" is Larisa, the administrator. A pale and nondescript person, in the past - also a stripper. However, about the latter, all the girls unanimously doubted: “What kind of stripper is she?! **** she, there is nowhere to put the stigma! On the very first night, I found out that the administrator Larisa herself was the initiator of violating the rules of the club (if it promises her income, of course) and, moreover, is quietly engaged in pandering. This was expressed in the fact that a good half of the girls were recruited not at all for dancing, and, in fact, they did not really know how to dance. But, having shown in the hall, so to speak, the goods in person (and in other places), Larisa organized post-club “privates” with clients for these girls. Of course, for a good bribe. These girls were called "privat". But the "angel" definitely did not belong to their number.

Meanwhile, the conflict continued. Dissatisfied "faces" also came to complain to the administrator's room and demand money back. They were outraged loudly and obscenely. I already wanted to intervene, but Ryba (Rybnikov, our shift supervisor, a short, stocky uncle from former cops), rudely stopped me:

Stay where you are! Still not enough - to start a fight because of these tattered cats!

I was uncomfortably struck by the malice evident in his voice. Why does he work here if he hates these girls so much?

Soon, Larisa still calmed the clients down by slipping them two "privates" who agreed to everything for a fee.

... The next few shifts went smoothly. I could relax and admire the dances: some of the girls danced so bewitchingly beautiful that it was a truly aesthetic pleasure.

A couple of times Igor Andreevich himself came in, whom now I could call the owner. He did not enter the hall, but stood in the doorway, watching, with his arms folded across his chest and an imperturbable expression on his face. But everyone immediately noticed him. And, I think, not only because of the tall growth (somewhere under two meters). Under his steely gaze, it seemed that even the strippers on the pylon began to spin somehow more cheerfully and more collected.

And I was still lost in his presence. And after all, he did not even look in my direction, but it was as if the soil was leaving from under my feet. There were some strange, contradictory sensations. I wanted to run away, hide, become as inconspicuous as possible, but instead I caught myself trying to catch his eye, to get his attention. What for? Then I did not find a single reasonable answer to this question, and unreasonable ones simply did not occur to me.

The study of physics at school lasts several years. At the same time, students are faced with the problem that the same letters denote completely different quantities. Most often, this fact is Latin letters. How then to solve problems?

There is no need to be afraid of such a repetition. Scientists tried to introduce them into the designation so that the same letters did not meet in one formula. Most often, students come across the Latin n. It can be lowercase or uppercase. Therefore, the question logically arises of what n is in physics, that is, in a certain formula that the student encountered.

What does the capital letter N stand for in physics?

Most often in the school course, it occurs in the study of mechanics. After all, there it can be immediately in spirit values ​​- the power and strength of the normal reaction of the support. Naturally, these concepts do not intersect, because they are used in different sections of mechanics and are measured in different units. Therefore, it is always necessary to define exactly what n is in physics.

Power is the rate of change in the energy of a system. It is a scalar value, that is, just a number. Its unit of measurement is the watt (W).

The force of the normal reaction of the support is the force that acts on the body from the side of the support or suspension. In addition to a numerical value, it has a direction, that is, it is a vector quantity. Moreover, it is always perpendicular to the surface on which the external action is performed. The unit of this N is the newton (N).

What is N in physics, in addition to the quantities already indicated? It could be:

the Avogadro constant;

magnification of the optical device;

substance concentration;

Debye number;

total radiation power.

What can a lowercase n stand for in physics?

The list of names that can be hidden behind it is quite extensive. The designation n in physics is used for such concepts:

refractive index, and it can be absolute or relative;

neutron - a neutral elementary particle with a mass slightly greater than that of a proton;

frequency of rotation (used to replace the Greek letter "nu", as it is very similar to the Latin "ve") - the number of repetitions of revolutions per unit of time, measured in hertz (Hz).

What does n mean in physics, besides the already indicated values? It turns out that the main quantum number is hidden behind it ( the quantum physics), concentration and Loschmidt constant (molecular physics). By the way, when calculating the concentration of a substance, you need to know the value, which is also written in the Latin "en". It will be discussed below.

What physical quantity can be denoted by n and N?

Its name comes from the Latin word numerus, in translation it sounds like "number", "quantity". Therefore, the answer to the question of what n means in physics is quite simple. This is the number of any objects, bodies, particles - everything that is discussed in a particular task.

Moreover, “quantity” is one of the few physical quantities that do not have a unit of measure. It's just a number, no name. For example, if the problem is about 10 particles, then n will be equal to just 10. But if it turns out that the lowercase “en” is already taken, then you have to use an uppercase letter.

Formulas that use an uppercase N

The first of them defines the power, which is equal to the ratio of work to time:

In molecular physics, there is such a thing as the chemical amount of a substance. Denoted by the Greek letter "nu". To calculate it, you should divide the number of particles by the Avogadro number:

By the way, the last value is also denoted by the so popular letter N. Only it always has a subscript - A.

To determine the electric charge, you need the formula:

Another formula with N in physics - oscillation frequency. To calculate it, you need to divide their number by the time:

The letter "en" appears in the formula for the circulation period:

Formulas that use a lowercase n

In a school physics course, this letter is most often associated with the refractive index of matter. Therefore, it is important to know the formulas with its application.

So, for the absolute refractive index, the formula is written as follows:

Here c is the speed of light in vacuum, v is its speed in a refracting medium.

The formula for the relative refractive index is somewhat more complicated:

n 21 \u003d v 1: v 2 \u003d n 2: n 1,

where n 1 and n 2 are the absolute refractive indices of the first and second medium, v 1 and v 2 are the speeds of the light wave in these substances.

How to find n in physics? The formula will help us with this, in which we need to know the angles of incidence and refraction of the beam, that is, n 21 \u003d sin α: sin γ.

What is n equal to in physics if it is the index of refraction?

Typically, tables give values ​​for the absolute refractive indices of various substances. Do not forget that this value depends not only on the properties of the medium, but also on the wavelength. Tabular values ​​of the refractive index are given for the optical range.

So, it became clear what n is in physics. To avoid any questions, it is worth considering some examples.

Power Challenge

№1. During plowing, the tractor pulls the plow evenly. In doing so, it applies a force of 10 kN. With this movement for 10 minutes, he overcomes 1.2 km. It is required to determine the power developed by it.

Convert units to SI. You can start with force, 10 N equals 10,000 N. Then the distance: 1.2 × 1000 = 1200 m. The time left is 10 × 60 = 600 s.

Choice of formulas. As mentioned above, N = A: t. But in the task there is no value for work. To calculate it, another formula is useful: A \u003d F × S. The final form of the formula for power looks like this: N \u003d (F × S): t.

Decision. We calculate first the work, and then the power. Then in the first action you get 10,000 × 1,200 = 12,000,000 J. The second action gives 12,000,000: 600 = 20,000 W.

Answer. Tractor power is 20,000 watts.

Tasks for the refractive index

№2. The absolute refractive index of glass is 1.5. The speed of light propagation in glass is less than in vacuum. It is required to determine how many times.

There is no need to convert data to SI.

When choosing formulas, you need to stop at this one: n \u003d c: v.

Decision. It can be seen from this formula that v = c: n. This means that the speed of light in glass is equal to the speed of light in vacuum divided by the refractive index. That is, it is reduced by half.

Answer. The speed of light propagation in glass is 1.5 times less than in vacuum.

№3. There are two transparent media. The speed of light in the first of them is 225,000 km / s, in the second - 25,000 km / s less. A ray of light goes from the first medium to the second. The angle of incidence α is 30º. Calculate the value of the angle of refraction.

Do I need to convert to SI? Speeds are given in off-system units. However, when substituting into formulas, they will be reduced. Therefore, it is not necessary to convert speeds to m/s.

The choice of formulas needed to solve the problem. You will need to use the law of light refraction: n 21 \u003d sin α: sin γ. And also: n = c: v.

Decision. In the first formula, n 21 is the ratio of the two refractive indices of the substances under consideration, that is, n 2 and n 1. If we write down the second indicated formula for the proposed environments, then we get the following: n 1 = c: v 1 and n 2 = c: v 2. If you make the ratio of the last two expressions, it turns out that n 21 \u003d v 1: v 2. Substituting it into the formula for the law of refraction, we can derive the following expression for the sine of the angle of refraction: sin γ \u003d sin α × (v 2: v 1).

We substitute the values ​​of the indicated velocities and the sine of 30º (equal to 0.5) into the formula, it turns out that the sine of the angle of refraction is 0.44. According to the Bradis table, it turns out that the angle γ is 26º.

Answer. The value of the angle of refraction is 26º.

Tasks for the period of circulation

№4. The blades of a windmill rotate with a period of 5 seconds. Calculate the number of revolutions of these blades in 1 hour.

To convert to SI units, only the time is 1 hour. It will be equal to 3600 seconds.

Selection of formulas. The period of rotation and the number of revolutions are related by the formula T \u003d t: N.

Decision. From this formula, the number of revolutions is determined by the ratio of time to period. Thus, N = 3600: 5 = 720.

Answer. The number of revolutions of the mill blades is 720.

№5. The aircraft propeller rotates at a frequency of 25 Hz. How long does it take the screw to complete 3,000 revolutions?

All data is given with SI, so nothing needs to be translated.

Required Formula: frequency ν = N: t. From it it is only necessary to derive a formula for the unknown time. It is a divisor, so it is supposed to be found by dividing N by ν.

Decision. Dividing 3,000 by 25 results in the number 120. It will be measured in seconds.

Answer. An airplane propeller makes 3000 revolutions in 120 s.

Summing up

When a student encounters a formula containing n or N in a physics problem, he needs to deal with two things. The first is from which section of physics the equality is given. This may be clear from the heading in a textbook, reference book, or the teacher's words. Then you should decide what is hidden behind the many-sided "en". Moreover, the name of the units of measurement helps in this, if, of course, its value is given. Another option is also allowed: carefully look at the rest of the letters in the formula. Perhaps they will be familiar and will give a hint in the issue being resolved.

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