NCERT Solutions for class 11 Physics | Chapter 15 - Waves
Questions
1
A transverse harmonic wave on a string is described by y (x,t ) = 3.0 sin (36t + 0.018x + π/4) where x and y are in cm and t is in s. The positive direction of x is from left to right.
Answer:A, B, C
2
A train whistling at constant frequency is moving towards a station at a constant speed V. The train goes past a stationary observer on the station. The frequency n′ of the sound as heard by the observer is plotted as a function of time t (Fig. in below) . Identify the expected curve.
Answer:(c)
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3
A string of mass 2.5 kg is under a tension of 200 N. The length of the stretched string is 20.0 m. If the transverse jerk is struck at one end of the string, the disturbance will reach the other end in
Answer:0.5 second
4
A sound wave is passing through air column in the form of compression and rarefaction. In consecutive compressions and rarefactions,
Answer:there is no transfer of heat.
5
Which of the following statements are true for wave motion?
Answer:Mechanical transverse waves can propagate through solids only.
6
With propagation of longitudinal waves through a medium, the quantity transmitted is
Answer:energy.
7
Change in temperature of the medium changes
Answer:wavelength of sound waves.
8
Water waves produced by a motor boat sailing in water are
Answer:both longitudinal and transverse.
10
The extension in a string , obeying Hookes law is X . The speed of sound in the stretched string is V . If the extension in the string is increased to 1.5 X , the speed of sound will be
Answer:1.22 V
11
The equation of wave traveling along string is y = 3 cos p (100t - x) in C.G.S. unit then wavelength is
Answer:2 cm
12
The frequency of the note produced by plucking a given string increases as
Answer:The tension in the string increases
13
If the phase difference between two points is 60o on a wave velocity of 360 m/s and frequency 500 Hz , then path difference between the two points is
Answer:12 cm
14
A simple harmonic wave having amplitude A and time period T is represented by the equation y = 5 sin p(t + 4) metres. Then the value of A (in metres) and T (in seconds) are
Answer:A = 5, T = 2
15
Which of the following expressions is that of a simple harmonic progressive wave
Answer: a sin (wt - kx)
16
A tuning fork of frequency 480 Hz is in unison with pipe closed at one end vibrating in its first overtone. Then fundamental frequency of the pipe is
Answer:480 Hz
17
In stationary waves
Answer:Energy is minimum at nodes and maximum at antinodes
19
A resonance air column of length 40 cm resonates with a tuning fork of frequency 450 Hz . Lgnoring end correction , the velocity of sound in air will be
Answer:720 m/s
20
Two closed pipe produces 10 beats per second when emitting their fundamental nodes. If their lengths are in the ratio of 25: 26 their fundamental frequency in Hz are
Answer:260, 250
Chapters
- Physical World
- Units and measurements
- Motion in a straight line
- Motion in a plane
- Laws of motion
- Work energy and power
- System of particles and rotational motion
- Gravitation
- Mechanical properties of solids
- Mechanical properties of fluids
- Thermal properties of matter
- thermodynamics
- Kinetic theory
- Oscillations
- Waves
