# Electromagnetic Waves Nootan Solutions ISC Class-12 Physics Nageen Prakashan

Electromagnetic Waves Nootan Solutions ISC Class-12 Physics Nageen Prakashan Chapter-13 Solved Numericals. Step by step Solutions of Kumar and Mittal ISC Physics Class-12 Nageen Prakashan Numericals Questions. Visit official Website for detail information about ISC Board Class-12 Physics.

## Electromagnetic Waves Nootan Solutions ISC Class-12 Physics Nageen Prakashan Chapter-13 Solved Numericals

 Class: 12 Subject: Physics Chapter 13: Electromagnetic Waves
 Board ISC Writer /Publications Nootan / Nageen Prakashan/Kumar and Mittal Topics Solved Numericals Page 587 to 612

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Electromagnetic Waves Nootan Solutions ISC Class-12 Physics Nageen Prakashan Chapter-13 Solved Numericals

Elementary facts about the uses of electromagnetic waves:
(i) In radio and TV communication.
(ii) In astronomical field.
Microwaves
(ii) In analysis of molecular and atomic structure.
(iii) For cooking purpose.
Infrared waves
(i) In knowing molecular structure. (ii) In remote control of TV VCR, etc.
Ultraviolet rays:

(i) Used in burglar alarm. (ii ) To kill germs in minerals.
X-rays
(i) In medical diagnosis as they pass through the muscles not through the bones.
(ii) In detecting faults, cracks, etc., in metal products,
γ-rays
(i) As food preservation. (ii) In radiotherapy.

Electromagnetic Waves: An electromagnetic wave is a wave radiated by an accelerated or oscillatory charge in which varying magnetic field is the source of electric field and varying electric field is the source of magnetic field. Thus two fields becomes source of each other and the wave propagates in a direction perpendicular to both the fields.

Need for Displacement Current Ampere’s circuital law for conduction current during charging of a capacitor was found inconsistent. Therefore, Maxwell modified Ampere’s circuital law.
The displacement current produces in space due to change of electric flux linked with the surface. This reveals that, varying electric field is the source of magnetic field.

#### Displacement Current

It is a current which produces in the region in which the electric field and hence the electric flux changes with time.

Displacement current, ID = εo . dφE / dt

where, φE is the electric flux.

#### Modulation:

The process of superimposing the audio signal over a high frequency carrier wave is called modulation.

In the process of modulation anyone characteristic of carrier wave is varied in accordance with the instantaneous value of audio signal (modulating signal).

Need of Modulation

(i) Energy carried by low frequency audio waves (20 Hz to 20000 Hz) is very small.

(ii) For efficient radiation and reception of signal. the transmitting and receiving antennas should be very high approximately 5000 m.

(iii) The frequency range of audio signal is so small that overlapping of signals create a confusion.

#### Demodulation:

The process of separating of audio signal from modulated signal is called demodulation.

Antenna

An antenna converts electrical energy into electromagnetic waves at transmitting end and pick up transmitted signal at receiving end and converts electromagnetic waves into electrical signal.

Modem

The term modem is contraction of the term modulator and demodulator. Modem is a device which can modulate as well as demodulate the signal. It connect one computer to another through ordinary telephone lines.

Fax (Facsimile Telegraphy)

The electronic reproduction of a document at a distant place is called FAX

### Electromagnetic Waves Nootan Solutions ISC Class-12 Physics Nageen Prakashan Chapter-13 Solved Numericals

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—: End of Electromagnetic Waves Alternating Currents Numericals :–

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