NCERT Physics Class 11 Exemplar Ch 15 Waves Part 5
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Long Answer
32. The earth has a radius of 6400 km. The inner core of 1000 km radius is solid. Outside it, there is a region from 1000 km to a radius of 3500 km which is in molten state. Then again from 3500 km to 6400 km the earth is solid. Only longitudinal (P) waves can travel inside a liquid. Assume that the P wave has a speed of 8 km in solid parts and of 5 km in liquid parts of the earth. An earthquake occurs at some place close to the surface of the earth. Calculate the time after which it will be recorded in a seismometer at a diametrically opposite point on the earth if wave travels along diameter?
Ans:
33. If c is R.M.S. speed of molecules in a gas and v is the speed of sound waves in the gas, show that c/v is constant and independent of temperature for all diatomic gases.
Ans:
for diatomic gases.
34. Given below are some functions of x and t to represent the displacement of an elastic wave.
(a)
(b)
(c)
(d)
State which of these represent
(a) A travelling wave along direction
(b) A stationary wave
(c) Beats
(d) A travelling wave along direction.
Given reasons for your answers.
Ans:
(a) (ii),
(b) (iv),
(c) (iii),
(d) (i).
35. In the given progressive wave
Where y and x are in m, t is in s. What is the
(a) Amplitude
(b) Wave length
(c) Frequency
(d) Wave velocity
(e) Particle velocity amplitude.
Ans:
(a)
(b)
(c)
(d)
(e) .
36. For the harmonic travelling wave where x and y are in cm and t is second. What is the phase difference between the oscillatory motions at two points separated by a distance of?
(a) 4 m
(b)
(c)
(d) (at a given instant of time)
(e) What is the phase difference between the oscillation of a particle located at at and?
Ans:
(a) Radian,
(b) radian,
(c) radian,
(d)
(e)