/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 32 A spherical mirror is polished o... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

A spherical mirror is polished on both sides. When the concave side is used as a mirror, the magnification is \(+2.0 .\) What is the magnification when the convex side is used as a mirror, the object remaining the same distance from the mirror?

Short Answer

Expert verified
The magnification with the convex side is \( \frac{2}{3} \).

Step by step solution

01

Understanding Magnification in Mirrors

Magnification (\( m \)) for mirrors is defined as the ratio of the image height (\( h' \)) to the object height (\( h \)). It is also expressed in terms of the image distance (\( v \)) and object distance (\( u \)) as:\[ m = -\frac{v}{u}\]For the concave mirror, we know that the magnification is given as +2.0. This indicates the image is upright and virtual, as positive magnification for mirrors indicates these characteristics.
02

Relating Object Distance for Both Configurations

Since the object distance (\( u \)) remains the same for both the concave and convex side uses, we can use the same object distance (let's call it \( u \)) for the convex mirror scenario as well. We have:\[m_{concave} = -\frac{v_{concave}}{u} = +2.0\]Thus, \( v_{concave} = -2.0u \). This information will help us determine the focal length for the concave side.
03

Finding the Focal Length of the Mirror

For a concave mirror, the mirror equation is:\[\frac{1}{f} = \frac{1}{u} + \frac{1}{v}\]Substitute \( v_{concave} = -2.0u \) into the equation:\[\frac{1}{f} = \frac{1}{u} - \frac{1}{2.0u} = \frac{2.0u - u}{2.0u^2} = \frac{1}{2.0u}\]Thus, the focal length for the concave side is \( f = 2.0u \).
04

Using Convex Side and Calculating Magnification

Since the surfacing of the mirror can be assumed as the same material, the radius of curvature remains consistent, implying the focal lengths of the concave and convex sides are the same magnitude but opposite in sign. Hence, the focal length for the convex side is \( f = -2.0u \).For the convex mirror, we use the same mirror equation:\[\frac{1}{f} = \frac{1}{u} + \frac{1}{v}\]where \( f = -2.0u \). Solving for this:\[\frac{1}{-2.0u} = \frac{1}{u} + \frac{1}{v_{convex}}\]Rearranging terms:\[\frac{1}{v_{convex}} = \frac{1}{-2.0u} - \frac{1}{u}\]\[\frac{1}{v_{convex}} = \frac{-1 - 2.0}{2.0u} = \frac{-3}{2.0u}\]Thus, \( v_{convex} = -\frac{2.0u}{3} \). This gives the magnification for the convex side as \( m_{convex} = -\frac{-\frac{2.0u}{3}}{u} = \frac{2.0}{3} \).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Concave Mirrors
Concave mirrors are spherical mirrors that curve inward, resembling a portion of a sphere. These mirrors focus light to a single point, called the focal point.
When light rays parallel to the mirror's principal axis strike the concave surface, they reflect and converge at the focal point. Here are some key features of concave mirrors:
  • They can form real, inverted images or virtual, upright images.
  • A virtual image is formed when the object is within the focal length.
  • These mirrors are commonly used in applications like telescopes and headlights.
In the exercise, the concave mirror provided a positive magnification, indicating an upright and virtual image.
Convex Mirrors
Convex mirrors are spherical mirrors that curve outward. Unlike concave mirrors, they cause light rays to diverge upon reflection, making them appear to originate from a focal point behind the mirror.
Here are essential aspects of convex mirrors:
  • They always form virtual, upright, and reduced images.
  • Convex mirrors are often used for rearview mirrors in vehicles due to their wide field of view.
In the exercise, the convex mirror produced a reduced magnification, reflecting the image characteristics typical of this mirror type.
Focal Length
The focal length of a mirror is the distance between the mirror's surface and its focal point. It plays a crucial role in determining how an image forms. For spherical mirrors:
  • The focal length ( f ) is half the radius of curvature of the mirror.
  • For concave mirrors, the focal length is positive, meaning the focal point is in front of the mirror.
  • For convex mirrors, it's negative, indicating the focal point lies behind the mirror.
Understanding focal length helps in applying the mirror formula, which relates the object distance, image distance, and focal length together.
Magnification
Magnification in the context of mirrors measures how much larger or smaller the image is compared to the object. It's expressed by the formula:
\[ m = \frac{h'}{h} = -\frac{v}{u} \]
Where ( m ) is magnification, ( h' ) is image height, ( h ) is object height, ( v ) is image distance, and ( u ) is object distance.
Key points about magnification:
  • A positive magnification indicates an upright image.
  • A negative magnification indicates an inverted image.
  • In the exercise, we saw positive magnification with the concave mirror and a less-than-one positive value with the convex mirror, reflecting reduced size.
This understanding is valuable when predicting image characteristics in various optical devices.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

An object is placed in front of a convex mirror. Draw the convex mirror (radius of curvature \(=15 \mathrm{cm}\) ) to scale, and place the object \(25 \mathrm{cm}\) in front of it. Make the object height \(4 \mathrm{cm} .\) Using a ray diagram, locate the image and measure its height. Now move the object closer to the mirror, so the object distance is \(5 \mathrm{cm} .\) Again, locate its image using a ray diagram. As the object moves closer to the mirror, (a) does the magnitude of the image distance become larger or smaller, and (b) does the magnitude of the image height become larger or smaller? (c) What is the ratio of the image height when the object distance is \(5 \mathrm{cm}\) to its height when the object distance is \(25 \mathrm{cm} ?\) Give your answer to one significant figure.

The image produced by a concave mirror is located \(26 \mathrm{cm}\) in front of the mirror. The focal length of the mirror is \(12 \mathrm{cm} .\) How far in front of the mirror is the object located?

A plane mirror and a concave mirror \((f=8.0 \mathrm{cm})\) are facing each other and are separated by a distance of \(20.0 \mathrm{cm} .\) An object is placed between the mirrors and is \(10.0 \mathrm{cm}\) from each mirror. Consider the light from the object that reflects first from the plane mirror and then from the concave mirror. Using a ray diagram drawn to scale, find the location of the image that this light produces in the concave mirror. Specify this distance relative to the concave mirror.

An object is placed \(11 \mathrm{cm}\) in front of a concave mirror whose focal length is \(18 \mathrm{cm} .\) The object is \(3.0 \mathrm{cm}\) tall. Using a ray diagram drawn to scale, measure (a) the location and (b) the height of the image. The mirror must be drawn to scale.

You walk at an angle of \(\theta=50.0^{\circ}\) toward a plane mirror, as in the drawing. Your walking velocity has a magnitude of \(0.90 \mathrm{m} / \mathrm{s}\). What is the velocity of your image relative to you (magnitude and direction)?

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.