Electromagnetic Waves

The apparent change in the frequency of the source due to a relative motion between the source and observer is known as Doppler's effect.
The perceived frequency is given by where is original frequency, the speed of sound, of observer, the speed of source.
In the given case there is no relative motion between source and observer,
since both are at rest, hence frequency of sound heard by the observer will remain unchanged.

Beats are the periodic and repeating fluctuations heard in the intensity of sound, when two sound waves of very similar frequencies interfere with one another.
Beats = difference in frequencies.
Maximum-number of beats

For an open pipe of length , the frequency is given by

where is velocity of sound, the overtone.
Given, and ,
and


Hence, this is the second overtone or third harmonic.

Electromagnetic waves are not deflected in electric and magnetic field.

The standard equation is

Dividing and multiplying the given equation by 2 , we get

On comparing Eqs. (i) and (ii), we get
units

In free space speed of electromagnetic wave


Thus, the value of electromagnetic wave is constant and cannot be changed by changing any of the given factors.

Crystal structure can be studied using -rays.

Answer (b) Radio waves, microwaves, infrared, visible light. X-rays

Phenomena of restricting the vibration of light.in a particular direction is called polarization, it helps to prove the transverse nature of electromagnetic waves.

Radio waves have maximum wavelength in the range of to .

gamma rays < microwaves < FM radiowaves < AM radiowaves

Sound wave is not an electromagnetic wave. It is a mechanical wave. When sound wave propagates, particles of the medium oscillates along the direction of propagation of the wave.

Answer (d) -rays

Step 1: Understand the source of electromagnetic waves.
Electromagnetic waves are produced by accelerating charges.
This can happen when a charge moves back and forth or experiences acceleration, causing a disturbance in the electric and magnetic fields that propagates as an electromagnetic wave.
Step 2: Identify the correct option.
Only an accelerating charge can produce a propagating electromagnetic wave.
A stationary charge or charge moving at a constant speed does not create such waves.

Step 1: Understand the concept of Transverse Electromagnetic Waves (TEM).
Transverse electromagnetic waves have both electric and magnetic fields that are perpendicular to the direction of propagation.
This type of wave can propagate in specific transmission lines like waveguides.
Step 2: Identify the transmission line types.
Rectangular waveguides are designed to support the propagation of TEM waves.
Coaxial cables and copper cables typically support either TE (Transverse Electric) or TM (Transverse Magnetic) modes rather than the TEM mode.