Huygens' Principle and Wavefronts

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JEE Advanced 2007

Comprehension Passage

X Y

separating two transparent media, medium-1 and medium-2. The lines

ab

and

c d

represent wavefronts of a light wave travelling in medium-1 and incident on

X Y

. The lines

e f

and

g h

represent wavefronts of the light wave in medium-2 after refraction.

Question 1:

Light travels as a

(A)

parallel beam in each medium

(B)

convergent beam in each medium

(C)

divergent beam in each medium

(D)

divergent beam in one medium and convergent beam in the other medium

Question 2:

The phases of the light wave at $c, d, e$ and $f$ are $ϕ_{c}, ϕ_{d}, ϕ_{e}$ and $ϕ_{f}$ respectively. It is given that $ϕ_{c} \neq = ϕ_{f}$

(A)

ϕ_{c}

cannot be equal to

ϕ_{d}

(B)

ϕ_{d}

can be equal to

ϕ_{e}

(C)

(ϕ_{d} - ϕ_{f})

is equal to

(ϕ_{c} - ϕ_{e})

(D)

(ϕ_{d} - ϕ_{c})

is not equal to

(ϕ_{f} - ϕ_{e})

Question 3:

Speed of light is

(A)

the same in medium-1 and medium-2

(B)

larger in medium-1 than in medium-2

(C)

larger in medium-2 than in medium-1

(D)

different at

b

and

d

JEE Advanced 2020

LEVELJEE Main

A parallel beam of light strikes a piece of transparent glass having cross section as shown in the figure below. Correct shape of the emergent wavefront will be (figures are schematic and not drawn to scale)-

A monochromatic light wave is incident normally on a glass slab of thickness d, as shown in the figure. The refractive index of the slab increases linearly from $n_{1}$ to $n_{2}$ over the height h. Which of the following statement(s) is (are) true about the light wave emerging out of the slab ?

* Multiple Correct Options

(A)

It will deflect up by an angle

tan^{- 1} [\frac{( n _{2}^{2} - n _{1}^{2} ) d}{2 h}]

(B)

It will deflect up by an angle

tan^{- 1} [\frac{( n _{2} - n _{1} ) d}{h}]

(C)

It will not deflect.

(D)

The deflection angle depends only on

(n_{2} - n_{1})

and not on the individual values of

n_{1}

and

n_{2}

LEVELJEE Main

The initial shape of the wavefront of the beam is

convex near the axis and concave near the periphery

As the beam enters the medium, it will

diverge near the axis and converge near the periphery

(D)

travel as a cylindrical beam

JEE Main 2015

LEVELJEE Main

On a hot summer night, the refractive index of air is smallest near the ground and increases with 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

(A)

becomes narrower

(B)

goes horizontally without any deflection

Comprehension Passage

Light travels as a

.math-text-wrapper .katex { font-size: 1.05em !important; } .math-text-wrapper .katex-display { margin: 1rem 0 !important; } The phases of the light wave at c,d,e and f are ϕc​,ϕd​,ϕe​ and ϕf​ respectively. It is given that ϕc​=ϕf​

Speed of light is

A parallel beam of light strikes a piece of transparent glass having cross section as shown in the figure below. Correct shape of the emergent wavefront will be (figures are schematic and not drawn to scale)-

The initial shape of the wavefront of the beam is

As the beam enters the medium, it will

On a hot summer night, the refractive index of air is smallest near the ground and increases with 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

The phases of the light wave at $c, d, e$ and $f$ are $ϕ_{c}, ϕ_{d}, ϕ_{e}$ and $ϕ_{f}$ respectively. It is given that $ϕ_{c} \neq = ϕ_{f}$