wave optics 2

Question 1

total internal reflection

Answer 1

The angle ic
is known as the critical angle and
for all angles of incidence greater than the critical angle, we will not have
any refracted wave and the wave will undergo what is known as total
internal reflection.

Question 2

When monochromatic light is incident on a surface separating
two media, the reflected and refracted light both have the same
frequency as the incident frequency. Explain why?

Answer 2

Reflection and refraction arise through interaction of incident light
with the atomic constituents of matter. Atoms may be viewed as
oscillators, which take up the frequency of the external agency
(light) causing forced oscillations. The frequency of light emitted by
a charged oscillator equals its frequency of oscillation. Thus, the
frequency of scattered light equals the frequency of incident light

Question 3

When light travels from a rarer to a denser medium, the speed
decreases. Does the reduction in speed imply a reduction in the
energy carried by the light wave?

Answer 3

No. Energy carried by a wave depends on the amplitude of the
wave, not on the speed of wave propagation.

Question 4

In the wave picture of light, intensity of light is determined by the
square of the amplitude of the wave. What determines the intensity
of light in the photon picture of light

Answer 4

For a given frequency, intensity of light in the photon picture is
determined by the number of photons crossing an unit area per
unit time

Question 5

interference is based on?

Answer 5

the entire field of
interference is based on the superposition
principle according to which at a particular
point in the medium, the resultant
displacement produced by a number of
waves is the vector sum of the displace
ments produced by each of the waves.

Question 6

condition for constructive interference

Answer 6

I = 4 I° cos ²(⌀/2)
⌀= 0, +-2 pi, +-4pi ,…

Question 7

condition for destructive interference

Answer 7

I = 4 I° cos ²(⌀/2)
⌀ = +-pi, +-3 pi, +-5pi…

Question 8

transverse wave.

Answer 8

Since the
displacement (which is along the y direction) is at right angles to the
direction of propagation of the wave, we have what is known as a
transverse wave.

Question 9

-polarised wave.

Answer 9

Also, since the displacement is in the y direction, it is
often referred to as a y-polarised wave

Question 10

unpolarised wave.

Answer 10

if the plane of vibration of
the string is changed randomly in very short intervals of time, then we
have what is known as an unpolarised wave. Thus, for an unpolarised
wave the displacement will be randomly changing with time though it
will always be perpendicular to the direction of propagation.