HARD
11th CBSE
IMPORTANT
Earn 100

The earth has a radius of 6400 km. The inner core of1000 kmradius is solid. Outside it, there is a region from1000 km to a radius of 3500 km which is in the 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/s in solid parts and of 5 km/s in liquid parts of the earth. An earthquake occurs someplace 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.

Important Questions on Waves

HARD
11th CBSE
IMPORTANT
If c is RMS. speed of molecules in a gas and v is the speed of sound waves in the gas, show that c¯ is constant and independent of temperature for all diatomic gases.
EASY
11th CBSE
IMPORTANT

Given below are some functions of x and t to represent the displacement of an elastic wave.

(a) y=5cos(4x)sin20t

Determine the type of wave.

EASY
11th CBSE
IMPORTANT

Given below is a function of x and t to represent the displacement of an elastic wave.

 y=4sin5x-t2+3cos5x-t2

State which of the following conditions represent the given equation.
(a) a travelling wave along –x direction

(b) a stationary wave

(c) beats

(d) a travelling wave along +x direction

EASY
11th CBSE
IMPORTANT

Given below are some functions of x and t to represent the displacement of an elastic wave.

y=10 cos[(252-250)πt] cos[(252+250)πt]

State which of the following conditions represent the given equation.
(a) a travelling wave along –x direction

(b) a stationary wave

(c) beats

(d) a travelling wave along +x direction

EASY
11th CBSE
IMPORTANT

Given below are some functions of x and t to represent the displacement of an elastic wave.

 y=100cos(100πt+0.5x)

State which of the following conditions represent the given equation.
(a) a travelling wave along –x direction

(b) a stationary wave

(c) beats

(d) a travelling wave along +x direction

EASY
11th CBSE
IMPORTANT

In the given progressive wave y=5sin(100πt-0.4πx) where x, y are in m, and t is in seconds, What is the amplitude?

MEDIUM
11th CBSE
IMPORTANT

In the given progressive wave y=5sin(100πt-0.4πx) where x, y are in m, and t is in seconds, What is the 

(b) wave length

MEDIUM
11th CBSE
IMPORTANT

In the given progressive wave y=5sin(100πt-0.4πx) where x, y are in m, and t is in seconds, What is the

(c) frequency