Wave equation Quiz 1

Question 1

A light wave travelling at the speed of $$3	imes {{10}^{8}}	ext{ }m{{s}^{-1}}$$, if the frequency of the wave  is $$5\,Hz$$. Find the wavenumber of the light wave.

Accepted Answer

$$\dfrac{2\pi	imes 10^{-7}}{6}m^{-1}$$

Answer

$$\dfrac{2\pi	imes 10^{-7}}{5}m^{-1}$$

Answer

$$\dfrac{2\pi	imes 10^{-7}}{3}m^{-1}$$

Answer

$$\dfrac{2\pi	imes 10^{-7}}{4}m^{-1}$$

Question 2

An electromagnetic wave was found to have wavelength $$13\,m$$ .Find the angular frequency of this electromagnetic wave.

Accepted Answer

$$4.6	imes 10^{7}s^{-1}$$

Answer

$$3	imes 10^{7}s^{-1}$$

Answer

$$13	imes 10^{7}s^{-1}$$

Answer

$$6.4	imes 10^{7}s^{-1}$$

Question 3

If the wave equation of the wave is given as $$x(t)=A\ cos(\omega t+	heta )$$ , where $$	heta $$ is called as the phase shift of the waves, then which of the following is not true?

Accepted Answer

The waves are said to be out-of-phase if the phase shift is equal to zero.

Answer

The waves are said to be in-phase if the phase shift is equal to zero.

Answer

The waves are said to be out-of-phase if the phase shift is not equal to zero.

Answer

Cannot say

Question 4

Ramu was trying to understand the nature of waves. He observed that the speed of the wave depends on the frequency, wavelength of the wave. Then, he asks the following question -speed of the wave remains unchanged when

Accepted Answer

The medium through which the wave propagates remains the same.

Answer

The wavelength remains the same.

Answer

The frequency remains the same.

Answer

The frequency and wavelength remain the same.

Question 5

Karthik was travelling in a car, he observes the light waves coming from the other car. He then asked, what is the speed of the wave, if the wavenumber of light waves is $$12	ext{ }{{m}^{-1}}$$ and the frequency of light waves is $$10\ Hz$$?

Accepted Answer

$$\dfrac{5}{6}	ext{ }m{{s}^{-1}}$$

Answer

$$\dfrac{10\pi }{6}	ext{ }m{{s}^{-1}}$$

Answer

$$\dfrac{12\pi }{5}	ext{ }m{{s}^{-1}}$$

Answer

$$\dfrac{6}{5}	ext{ }m{{s}^{-1}}$$