Match List-I (Electromagnetic wave type) with List-II (Its association/application) and select the correct option from the choices given below the lists:
List I | List II | ||
A. | Infared waves | 1. | To treat muscular strain |
B. | Radio waves | 2. | For broadcasting |
C. | X -rays | 3. | To detect fracture of bones |
D. | Ultraviolet | 4. | Absorbed by the ozone layer of the atmosphere |
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 ωc and the signal frequency is denoted by ωm. The bandwidth (Δωm) of the signal is such that Δωm << ωc. 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
C.
2
p1 =po sin 2π(x- 1)t
p2 =po sin 2π(x)t
p3 =po sin 2π(x+ 1)t
p=p1+p3+p2
=posin2π(x-1)t +po sin 2π(x+1)t +po sin 2π(x)t
= 2posin2πxtcos2πt +posin2πxt
= 2posin2πxt[2cos πt +1]
⇒ fbeat = 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