A photon is a bundle of electromagnetic energy. It is the basic unit that makes up all light. The photon is sometimes referred to as a "quantum" of electromagnetic energy. They have zero mass. They have no electric charge. They are stable. They carry energy and momentum which are dependent on the frequency. They can have interactions with other particles such as electrons. They can be destroyed or created by many natural processes. When in empty space, they travel at the speed of light.

Green light of mercury has a wavelength of 5 .5 × 10 − 7 m in air. What is its frequency in MHz and period in s ?

Given wavelength of light λ = 5 . 5 × 10 - 7 m Assume velocity of light in air c = 3 × 10 8 m / s As the velocity is given by c = ν . λ where ν =frequency Putting the values in the formula, we have 3 × 10 8 = 5 . 5 × 10 - 7 × ν or ν = 3 . 0 × 10 8 5 . 5 × 10 - 7 = 5 . 45 × 10 14 Hz As time period = 1 frequenc y = 1 5 . 45 × 10 14 = 1 . 83 × 10 - 15 or 1 . 83 × 10 - 9 μs .

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A plane wavefront passing through a concave lens converges to a point.

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Important Questions on Wave Optics

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Physics>Optics>Wave Optics>Huygen’s Principle

How fast would a rocket have to go relative to an observer for its length to be corrected to $99 %$ of its length at rest? $(c = 3 \times 10^{8} {ms}^{- 1})$

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Physics>Optics>Wave Optics>Huygen’s Principle

A beam of electrons of energy E scatters from a target having atomic spacing of

1 Å

. The first maximum intensity occurs at

θ = 60 ° .

Then

E (in eV)

is........
(Planck's constant

h = 6.64 \times 10^{- 34} J s, 1 eV = 1.6 \times 10^{- 19} J,

electron mass

m = 9.1 \times 10^{- 31} kg

)

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Physics>Optics>Wave Optics>Huygen’s Principle

The wave front is a surface in which

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Physics>Optics>Wave Optics>Huygen’s Principle

Considering the fact that the speed of light in glass is not independent of the colour of light, which of the statement is true?

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Physics>Optics>Wave Optics>Huygen’s Principle

On a hot summer night, the refractive index of air is the smallest near the ground and increases with a height from the ground. When a light beam is directed horizontally, the Huygens' principle leads us to conclude that as it travels, the light beam,

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Physics>Optics>Wave Optics>Huygen’s Principle

The shape of wave front at a very large distance from source is ________.

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Physics>Optics>Wave Optics>Huygen’s Principle

When light propagates through a material medium of relative permittivity

ϵ_{r}

and relative permeability

μ_{r}

, the velocity of light,

v

is given by : (

c

- velocity of light in vacuum)

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Physics>Optics>Wave Optics>Huygen’s Principle

A beam of light with a plane wavefront needs to be transformed into one with a convergent spherical wavefront. For this purpose, which of the following may be suitable?

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Physics>Optics>Wave Optics>Huygen’s Principle

Light follows wave nature because

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Physics>Optics>Wave Optics>Huygen’s Principle

A radio transmitter operates at a frequency 0f

880 kHz

and a power of

10 kW

. The number of photons emitted per second are :

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Physics>Optics>Wave Optics>Huygen’s Principle

Does the speed of light in vacuum depend upon (i) nature of source, (ii) direction of propagation, (iii) intensity of the wave, (iv) motion of the source/observer, (v) wavelength?

MEDIUM

Physics>Optics>Wave Optics>Huygen’s Principle

The wavelength of an electromagnetic radiation is doubled, how will the energy of the photon change?

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Physics>Optics>Wave Optics>Huygen’s Principle

The phase difference between