Waves MCQ Level - 2 - Physics MCQ

The correct answer is :

Let a_i, and a_r be the amplitudes of incident and reflected waves. Then


∴ Fraction of energy reflected is

The correct answer is:

The given equation can be written as

y = 2(cost + 1) sin(1000t)
= 2cost sin 1000t + 2sin(1000t)
= sin(1001t) + sin(999t) + 2sin(1000t)
i.e. the given expression is a small of superposition of three independent harmonic motions of angular frequencies 999,1000 and 1001 rad/sec.
The correct answer is: Three

Only first equation is the equation of standing wave. The condition for a function x and t to represent a wave is :

Only first equation satisfies the condition.
The correct answer is: 

Wave velocity 
Maximum particle velocity 
Given, 
or 

The correct answer is:  

At t = 0, x = 5 cm, initial phase of insect

After 5s insect will more a distance s = vt = 25 cm
So, it will beat x = 30 cm .
At this instant,

The correct answer is: 

Apparent frequency for reflector (will act as an observer) would be :

where f = actual frequency of source.
After being reflected the apparent frequency will further change and the reflector will now behave as a source. The apparent frequency will now become :

Substituting value of f₁, we get

The correct answer is: 

Let v be the speed of sound and u the speed of train.

Then 
and

The correct answer is: is equal to f

Distance between two adjacent antinodes is
Volume of string between two adjacent antinodes 

Here, u is the energy density (energy per unit volume) which is equal to 

The correct answer is : 

 only when other properties like density of medium, speed of wave etc, remains the same 
In incident and reflected waves medium is same. Therefore, other properties are same. Hence,

The correct answer is: