Waves

Match List-I (Electromagnetic wave type) with List-II (Its association/application) and select the correct option from the choices given below the lists:

• A	B	C	D
  4	3	2	1

• A	B	C	D
  1	2	4	3

• A	B	C	D
  3	2	1	4

• A	B	C	D
  3	2	1	4

The transverse displacement y(x,t) of a wave on a string is given by

This represents a

• wave moving in +x direction with speed 

• wave moving in -x direction with speed 

• standing wave frequency 

• standing wave frequency 

In amplitude modulation, sinusoidal carrier frequency used is denoted by ω_c and the signal frequency is denoted by ωm. The bandwidth (Δω_m) of the signal is such that Δω_m << ω_c. Which of the following frequencies is not contained in the modulated wave?

• ωm + ωc

• ωc - ωm

• ωm

• ωm

An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the frequency of the microwave measured by the observer?
(speed of light = 3 × 10⁸ ms^–1)

• 17.3 GHz

• 15.3 GHz

• 10.1 GHz

• 10.1 GHz

Three sound waves of equal amplitudes have frequencies (ν – 1), ν, (ν + 1). They superpose to give beats. The number of beats produced per second will be.

• 4

• 3

• 2

• 2

A wave travelling along the x-axis is described by the equation y(x, t) = 0.005 cos (αx −βt). If the wavelength and the time period of the wave are 0.08 m and 2.0 s, respectively, then α and β in appropriate units are 

• α = 25.00 π, β = π

• α = 0.08/ π,  2.0/π

• α = 0.04 / π , β =1.0/π

• α = 0.04 / π , β =1.0/π

A whistle producing sound waves of frequencies 9500 Hz and above is approaching a stationary person with speed v ms⁻¹. The velocity of sound in air is 300 ms−1. If the person can hear frequencies upto a maximum of 10,000 Hz, the maximum value of v upto which he can hear the whistle is

• 
• 

• 15 ms^-1

• 15 ms^-1

When two tuning forks (fork 1 and fork 2) are sounded simultaneously, 4 beats per second are heard. Now, some tape is attached on the prong of the fork 2. When the tuning forks are sounded again, 6 beats per seconds are heard. If the frequency of fork 1 is 200 Hz, then what was the original frequency of fork 2?

• 200 Hz

• 202 Hz

• 196 Hz

• 196 Hz

An observer moves towards a stationary source of the sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency?

• 0

• 0.5%

• 5%

• 5%

The displacement y of a particle in a medium can be expressed as y = 10⁻⁶ sin(110t + 20 x + π/4) m, where t is in seconds and x in a meter. The speed of the wave is

• 2000 m/s

• 5 m/s

• 20 m/s

• 20 m/s