Rays and Light | 7

Question 1

Refractive index

Answer 1

Speed of light in vacuum / Speed of light in medium

‘n’

Question 2

Refractive index (Snell’s law)

Answer 2

Sin r ‘n’

Question 3

Refractive index (critical angle)

Answer 3

Sin c ‘n’

Question 4

Light properties

Answer 4

Travels in the form of transverse waves

Represented as a ray

Can travel through all mediums (including vacuum)

Made up of photons

Part of the electromagnetic waves family

Specific colors have diffract wavelengths

A object of color x reflects only x and absorbs all other colors

Question 5

Reflection of light

Answer 5

Bouncing back of light rays

(incident and reflected rays + point of incidence)

When a ray of light hits a smooth and shiny surface , they bounce back in a regular manner

When a ray of light falls on a rough surface , they bounce back in random directions

Question 6

What is the angle of incidence and reflection

Answer 6

the angle between their respective rays and the normal

Question 7

Laws of reflection on a plane mirror

Answer 7

∠i = ∠r

Incident ray , reflected ray and normal all lie on the same plane

Question 8

Nature of images formed on a plane mirror

Answer 8

Virtual

Same size

Same distance

Object , image are in same line

inverted sideways

Cannot be caught on screen

Question 9

Refraction of light

Answer 9

Light’s bending and speed changes when entering a new medium

Question 10

Dispersion

Answer 10

When white light goes through a prism , deferent colors come out because of their varying wavelengths

(Red has least frequency so it bends the least)

Question 11

Critical angle

Answer 11

It is the angle of incidence at which the refracted
ray goes at 90 degrees to the normal.

Question 12

TIR

Answer 12

Total internal reflection (TIR)

Ray bounces back to same medium

Question 13

Endoscopy

Answer 13

Doctor puts a optical fiber tube down a persons throat to observe organ because of TIR within the optic fiber

Question 14

TIR in diamonds

Answer 14

Causes Sparkle

Due to the cut of the diamond and its small critical which allows more TIR

Question 15

What types of lenses for what conditions in the eye

Answer 15

Hyperopia - convex (long sightedness)
Myopia - concave (short sightedness)

Question 16

Optic center

Answer 16

Center of the lens

Question 17

principal axis

Answer 17

imaginary line passing through optic center

Question 18

Principal focus

Answer 18

point where light rays meet

Question 19

Focal length

Answer 19

the distance between the centre of a lens or curved mirror and its focus.

Question 20

Human eye

Answer 20

The size of the lens is adjusted with the help of ciliary muscles.

This is to focus objects at different positions.
The rays converge on the retina.

The retina has light sensitive cells and sends the
information to the brain through the optic nerves.

Question 21

Lowest to highest frequency EM waves

Answer 21

Radio waves

Infrared waves

light

ultraviolet

x - ray

gamma rays

Question 22

Electro magnetic waves properties

Answer 22

Speed of light

can travel through every medium

Only light is visible

Transverse waves , carry energy