Popular Courses
Beginner – Linear Regression
Introduction
Beginner – Decision Trees
Introduction
Beginner – Neural Networks
Introduction

Sign in to Curvingo

or

New Account     Reset Password     

Plans

Details
Light – Reflection and Refraction
Introduction
Reflection of Light
Spherical Mirrors
Practice: Spherical Mirrors
Refraction of Light
Practice: Refraction and Refractive Index
Practice: Lenses, Lens Formula and Power
Chapter Review: Mixed Practice
Summary
Curvingo · Made in India

Share

Send us Feedback

Please let us know if you have any feedback and suggestions, or if you find any errors and bugs in our content.

Sorry, your message couldn’t be submitted. Please try again!

Thanks for your feedback!

Reset Progress

This will delete your progress and chat data for all chapters in this course, and cannot be undone!

Glossary

Select one of the keywords on the left…

Light – Reflection and RefractionReflection of Light

Reading time: ~15 min

A highly polished surface, such as a mirror, reflects most of the light that falls on it. You met the rules of reflection in earlier classes. Let us put them to work.

Drag the torch around the mirror and bounce its light into all three targets. The dashed line is the normal: the line at right angles to the mirror at the point where the light strikes it. Angles are measured from the normal.

To hit a target you had to put the torch at the same angle on the other side of the normal. That is the first law of reflection. Notice also that the torch beam, the normal and the reflected beam all lie in the plane of your screen.

Laws of reflection of light

(i) The angle of incidence is equal to the angle of reflection.

(ii) The incident ray, the normal to the mirror at the point of incidence and the reflected ray all lie in the same plane.

These laws hold for every reflecting surface, flat or curved. At each point of a curved mirror the light simply obeys them with that point's own normal.

Your Image in a Plane Mirror

You look at an image in a plane mirror every morning. Fill in what you already know about it.

You cannot catch this image on a screen, so it is , and it is the right way up, so it is .

It is you, and it is as far the mirror as you are in front of it.

Raise your right hand and your image raises its left: left and right are swapped. This is called lateral inversion. It explains a word you see on the road every day. Why is AMBULANCE painted in mirror writing on the front of an ambulance?

So that people on the footpath can read it easily
So that a driver ahead reads it the right way round in the rear-view mirror
Because it is painted from the inside of the bonnet

The rear-view mirror inverts the letters laterally once more, so the driver ahead reads AMBULANCE and makes way. So the image formed by a plane mirror is virtual and erect, the same size as the object, as far behind the mirror as the object is in front of it, and laterally inverted. What happens when the mirror is curved?

Activity 9.1: Faces in a Spoon

Pick up the biggest, shiniest steel spoon in your kitchen and look at your face in its curved surface. Move the spoon slowly away from your face and watch the image change. Then turn the spoon over and look again.

Held at arm's length, the inside of the spoon (the hollow) shows your face . The back of the spoon (the bulge) shows your face .

Bring the hollow very close to your eye, and the face flips the right way up and becomes large. The back keeps the face erect and small, however you hold it. So the two curved surfaces of one spoon behave very differently.

The shining surface of a spoon is a curved mirror. The most common curved mirrors are spherical mirrors: their reflecting surface is part of the surface of a sphere. Let us study them in detail.

Sina