Amplitude of a Wave

Q. 140. A radar sends radiowaves of frequency v towards an aeroplane moving with velocity vA.a change delta v is observed in the frequency of reflected wave which is higher than the original frequency.the velocity of aeroplane(vA<

Q. is there any method to remember the wavelength and frequency of EM WAVES ?

Q. The difference between the apparent frequency of a source as perceived by an observer during its approach and recession is 2 percent of the natural frequency of the source. The velocity of the source is

Q. A signal of frequency $10\text{kHz}$ and peak voltage of $10\text{V}$ is used to modulate a carrier of frequency $800\text{kHz}$ and peak voltage of $20\text{V}$. What is the amplitude modulation index?

1. $0.5$
2. $2.0$
3. $1.0$
4. $2.5$

Q. Two stationary sources each emit waves of wavelength lambda. An observer moves from one source to another with velocity u. Then number of beats Heard by him