/*! 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 54 Two plane mirrors are placed at ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Two plane mirrors are placed at some angle. There are five images formed, when an object is placed symmetrically between them, the angle between the mirrors is : (a) \(60^{\circ}\) (b) \(65^{\circ}\) (c) \(30^{\circ}\) (d) \(45^{\circ}\)

Short Answer

Expert verified
The angle between the mirrors is \(60^{\circ}\).

Step by step solution

01

Formula for images formed by plane mirrors

When two plane mirrors are placed at an angle \( \theta \), and an object is placed between them, the number of images \( n \) formed is given by the formula: \( n = \frac{360}{\theta} - 1 \) if \( \frac{360}{\theta} \) is an even number, or \( n = \frac{360}{\theta} \) otherwise.
02

Setting up the equation for given images

We are given that the number of images formed is 5. Thus, we set up the equation \( \frac{360}{\theta} - 1 = 5 \) or \( \frac{360}{\theta} = 5 \).
03

Solving for \( \theta \)

Solve the equation \( \frac{360}{\theta} - 1 = 5 \). Rearranging gives: \( \frac{360}{\theta} = 6 \).Multiply both sides by \( \theta \): \( 360 = 6\theta \) Dividing both sides by 6 gives: \( \theta = 60^{\circ} \).
04

Confirming the solution

Substitute \( \theta = 60^{\circ} \) back into the formula to confirm:\( \frac{360}{60} - 1 = 6 - 1 = 5 \)This matches the given condition of 5 images. Therefore, the solution is consistent with the problem statement.

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.

Image Formation
When plane mirrors are positioned at an angle, they create multiple images of any object placed between them. This fascinating phenomenon occurs because light reflects back and forth between the mirrors, generating additional images with each reflection. The number of images formed depends on the angle between the mirrors and can be calculated using a simple formula. A key concept to remember is that when mirrors are parallel, they produce infinite images due to continuous reflections. However, when they are angled, as in this problem, the number of reflections and, consequently, the images, becomes finite. This unique setup helps us understand how reflections work in practical applications, like periscopes and some decorative effects.
To predict how many images will appear, we rely on the formula related to the angle \( heta \) between the mirrors. This formula, described below, assists in visualizing how the object's reflection bounces within the mirror boundaries.
Angle Between Mirrors
Understanding the angle between mirrors is crucial for predicting image formation. In this exercise, reflecting on the arrangement of mirrors helps in determining how many images you might see. If two mirrors are set up at an angle \( heta \), the number of images \( n \) created is calculated using:

\[ = \frac{360}{\theta} - 1 \] (when \( \frac{360}{\theta} \) is even), or just \[ n = \frac{360}{\theta} \] if otherwise.

This formula is derived from the concept of circular geometry and reflection symmetries. As the formula implies, smaller angles result in more images. An angle of \( 60^{\circ} \) perfectly splits the circle into six parts, which means the object reflects multiple times before the light direction aligns back with the original. This exercise shows how the alignment and angling of mirrors precisely control the number of images seen, making it an intriguing part of geometric optics.
Geometrical Optics
Geometrical optics is the branch of optics that deals with the study of light in terms of rays. This helps us understand phenomena like reflection and refraction in a straightforward way. The laws of reflection are directly applicable when studying plane mirrors. According to these laws, the angle of incidence equals the angle of reflection. This predictable behavior of light allows us to comprehend how images are formed.
In the scenario with two plane mirrors, geometrical optics provides a framework to deduce not only how many images form but also where they appear. Drawing ray diagrams can be particularly effective in visualizing the paths light takes as it reflects between mirrors. Geometrical optics offers tools to examine various setups analytically, ensuring that complex interactions remain intuitive and understandable for learners and enthusiasts alike.
Reflection Formula
The reflection formula fundamentally governs how images appear on mirrors. For plane mirrors forming multiple images, the formula mentioned earlier helps calculate the number of images based on the mirror angle. This formula is a practical application of the laws of reflection which dictate that angles with respect to the normal (perpendicular) are consistent before and after bouncing off surfaces.
The formula is given by:

\[ = \frac{360}{\theta} - 1 \] if \( \frac{360}{\theta} \) is even
or \[ n = \frac{360}{\theta} \] otherwise.

This relationship arises because each reflection contributes to creating additional images, depending on how the mirrors are angled. By plugging in different angles, you can see how varying configurations change what is seen. Understanding this formula illuminates the predictable order within the seemingly complex interactions of light and mirrors, making it easier to grasp these captivating optical effects.

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

A ray is incident on a plane surface. If \(\hat{i}+\hat{j}-\hat{k}\) represents a vector along the direction of incident ray. \(\hat{i}+\hat{j}\) is a vector along normal on incident point in the plane of incident and reflected ray. Then vector along the direction of reflected ray is: (a) \(-\frac{1}{\sqrt{19}}(-3 \hat{\mathbf{i}}+3 \hat{j}+\mathbf{k})\) (b) \(\frac{1}{\sqrt{19}}(3 \hat{\mathrm{i}}+3 \hat{\mathrm{j}}-\cdot \hat{\mathrm{k}})\) (c) \(-\frac{1}{\sqrt{3}}(\hat{i}+\hat{j}+\hat{k})\) (d) \(\hat{\mathbf{k}}\)

Mark correct option : (a) The laws of reflection of light hold only for plane surfaces (b) The size of virtual image can be measured by receiving it on screen (c) Plane mirror alongs form an erect image (d) Plane mirror may form inverted image

A body of mass \(100 \mathrm{~g}\) is tied to one end of spring of constant \(20 \mathrm{~N} / \mathrm{m}\). The distance between pole of mirror and mean position of the body is \(20 \mathrm{~cm}\). The focal length of convex mirror is \(10 \mathrm{~cm}\). The amplitude of vibration of image is :(a) \(10 \mathrm{~cm}\) (b) \(50 \mathrm{~cm}\) (c) \(0.67 \mathrm{~cm}\) (d) \(0.33 \mathrm{~cm}\)

An object of height \(5 \mathrm{~cm}\) is placed in midway between a concave mirror of radius of curvature \(30 \mathrm{~cm}\) and a convex mirror of radius of curvature \(30 \mathrm{~cm}\). The mirrors are placed opposite to each other and are \(60 \mathrm{~cm}\) apart. The position of the image formed by reflection at convex mirror is : (a) \(10 \mathrm{~cm}\) (b) \(20 \mathrm{~cm}\) (c) \(15 \mathrm{~cm}\) (d) \(13 \mathrm{~cm}\)

A plane mirror is placed in \(y-z\) plane. A point object approaches the plane mirror with velocity \(3 \hat{1}+4 \hat{j}\). The velocity of image with respect to mirror is: (a) \(-3 \hat{\mathbf{i}}+4 \hat{\mathbf{j}}\) (b) \(3 \hat{i}-4 \hat{j}\) (c) \(-3 \hat{i}-4 \hat{j}\) (d) none of these

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.