Light- Reflection and Refraction

Question 1

Wavelength of light

Answer 1

400nm-700nm

Question 2

Explain how light is dual in nature?

Answer 2

It is of particle nature (photo electric effect) and wave nature (interference, diffraction and polarisation)

Question 3

Diffraction of light

Answer 3

When an opaque object obstructing the light rays pathway is very small, the light ray tends to bend around it, this is known as diffraction of light.

Question 4

Rectilinear propagation

Answer 4

The travelling of light in a straight line.

Question 5

Laws of reflection for plane mirror.

Answer 5

1.Virtual and erect
2.Equal distance
3.Same size
4.Laterally inverted

Question 6

Aperture

Answer 6

It is the diameter of the portion available for reflection

Question 7

Pole

Answer 7

Geometric centre of the aperture. Denoted by P

Question 8

Centre of curvature

Answer 8

Centre of the sphere the mirror is a part of. Denoted by C

Question 9

Principle axis

Answer 9

An imaginary line passing through the C, P & F.

Question 10

Radius of curvature

Answer 10

It is the radius of the sphere the mirror is a part of. Denoted by R

Question 11

Principal focus for concave mirror

Answer 11

A parallel beam converges at a point on the principle axis, this point is known as principle focus.

Question 12

Principle focus for convex mirror

Answer 12

A parallel beam appears to diverge from a point which is known as the principle focus.

Question 13

Focal length

Answer 13

Distance between the pole and the principle focus. Denoted by f

Question 14

Relation between f and R

Answer 14

2f=R

Question 16

Nature of image by concave mirror when object is at F

Answer 16

Real, inverted, highly magnified at infinity

Question 17

Diverging lense

Answer 17

Concave lens

Question 18

Nature of image by concave mirror when object is between P and F

Answer 18

Virtual , erect, magnifiedand behind mirror.

Question 19

Mirror formula

Answer 19

1/u + 1/v = 1/f

Question 20

Magnification (formula)

Answer 20

m = h1/h = v/u
h1/v = height of the image, h/u = height of the object

Question 21

Refraction

Answer 21

When light travels obliquely from one medium to another, the direction of propagation of light in the second medium changes, this is known as refraction of light.

Question 22

Snell’s law of refraction

Answer 22

The ratio of the sine of angle i and r angle is constant for light of a given colour and for the given pair of media

Question 23

Snell’s law (formula)

Answer 23

Sin i/ sin r = constant

Question 24

Refractive index

Answer 24

It is the extent of change in direction that takes place in a given pair of media

Question 25

Lens

Answer 25

It is a transparent material that is bound by two spherical surfaces OR one spherical and one plane surface

Question 26

Convex lens is also called...

Answer 26

Converging lens

Question 27

Concave lens is also called...

Answer 27

Diverging lens

Question 28

Concave mirror is also known as...

Answer 28

Converging mirror.

Question 30

Denser medium to rarer medium (travelling of light)

Answer 30

Faster and moves away from the normal

Question 31

Formula for refractive index...

Answer 31

n21= medium 1/ medium 2 =v1/v2

Question 34

Absolute refractive index

Answer 34

Taken w.r.t vacuum. Nm = c/v

Question 35

Rarer medium to denser medium (travelling of light)

Answer 35

Slows down and bends towards the normal

Question 36

Converging lens

Answer 36

Convex lens

Question 37

Optical centre

Answer 37

Central point of a lens