Answer the following questions:
Two students are separated by a 7 m partition wall in a room 10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see each other even though they can converse easily.

Solution

The size of the obstacle or aperture should be comparable to the wavelength for diffraction of waves by obstacles, through a large angle.

This follows from sin

θ = \frac{λ}{a}

.
For light waves,

Wavelength,

λ

= 10^-7 m and,
size of the wall, a = 10 m

∴ \sin θ = \frac{10^{- 7}}{10} = 10^{- 8}

This implies,

θ \to 0

That is, light goes almost unbent and hence, the students are unable to see each other.

For sound waves,

Frequency,

ν

= 1000 Hz

i.e.,

\frac{c}{ν} = \frac{330}{1000} = 0.33 m

∴

sin

θ = \frac{λ}{a} = \frac{0.33}{10} = 0.033 m

Here,

θ

has a definite value and the waves will bend around the partition. Hence, students can converse easily.

Some More Questions From Wave Optics Chapter

Let us list some of the factors which could possibly influence the speed of wave propagation:
(i) nature of source.
(ii) direction of propagation.
(iii) motion of source and/or observer.
(iv) wave length.
(v) intensity of the wave.
On which of these factors, if any, does
(a) the speed of light in vacuum,
(b) the speed of light in a medium (say, the glass or water) depend?

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Wave Optics

Answer the following questions:
Two students are separated by a 7 m partition wall in a room 10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see each other even though they can converse easily.

Some More Questions From Wave Optics Chapter

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

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For Daily Free Study Material Join wiredfaculty

Wave Optics

Answer the following questions:Two students are separated by a 7 m partition wall in a room 10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see each other even though they can converse easily.

Some More Questions From Wave Optics Chapter

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Answer the following questions:
Two students are separated by a 7 m partition wall in a room 10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see each other even though they can converse easily.