Q: A parallel plate capacitor made of circular plates is being charged such that the surface charge density on its plates is increasing at a constant rate with time. The magnetic field arising due to dis

aligned & I_d= _0 d _e d t = _0 d d t (E A 0^ ) \\ & I_d= _0 A d E d t \\ & E= _0 ; I_d= _0 A d d t ( _0 ) \\ & I_d=A ( d d t )= constant aligned Also B due to I_d is max ^m at surface of imaginary cylinder

Q: The electric field in a plane electromagnetic wave is given by E_z=60 (5 x +1.5 10^9 t ) V / m . Then expression for the corresponding magnetic field is (here subscripts denote the direction of the fi

aligned & v = k = 1.5 10^9 5 =3 10^8 ~m / s \\ & B _0= F _0 v = 60 3 10^8 =20 10^ -8 =2 10^ -7 ~T aligned B _ y =2 10^ -7 (5 x +1.5 10^9 t ) T

Question 1

An electromagnetic wave travelling in a lossless dielectric medium having a dielectric constant, _r=9, has the electric field, E_x=E_0 (kz-2 10^6 t) Vm^ -1 where E_0 is the amplitude and k is the wave

Accepted Answer

From the given equation of the electric field E_x = E_0 (kz - 2 10^6 t), the wave is propagating in the +z direction. The angular frequency is = 2 10^6 rad/s, which gives the frequency f = 2 = 10^6 Hz. The speed of the electromagnetic wave in the dielectric medium is given by v = c _r _r . Assuming a non-magnetic medium ( _r = 1), we get v = 3 10^8 9 = 10^8 ms^ -1 . The wavelength of the wave inside the medium is = v f = 10^8 10^6 = 100 m. Option (3) states the wavelength is 300 m, which is inco

Question 2

Match List I with List II : List I (Electromagnetic wave) List II (Production) A. Microwave I. Electrons in atoms emit light when they move from a higher energy level to a lower energy level B. Visibl

Accepted Answer

Microwaves are produced by special vacuum tubes such as klystron valves, magnetron valves, and Gunn diodes. Thus, A matches IV. Visible light is produced when electrons in atoms undergo transitions from a higher energy level to a lower energy level. Thus, B matches I. Gamma rays are produced during the radioactive decay of the nucleus and other nuclear reactions. Thus, C matches II. Infra-red rays are produced by hot bodies and molecules, specifically due to the vibration of atoms and molecules.

Question 3

The following table presents the part of the electromagnetic spectrum and their corresponding major applications. Part of the electromagnetic spectrum Applications P. Microwave I. For purifying the wa

Accepted Answer

Microwaves are used in microwave ovens for warming food, so P matches with II. Ultraviolet (UV) rays are used in water purifiers to kill bacteria and purify water, so Q matches with I. Gamma rays are highly energetic and are used in radiotherapy to destroy cancer cells, so R matches with IV. Radio waves are used in AM and FM radio communication systems, so S matches with III. The correct matching is P-II, Q-I, R-IV, S-III. Answer: P-II, Q-I, R-IV, S-III

Question 4

A parallel plate capacitor made of circular plates is being charged such that the surface charge density on its plates is increasing at a constant rate with time. The magnetic field arising due to dis

Accepted Answer

aligned & I_d= _0 d _e d t = _0 d d t (E A 0^ ) \ & I_d= _0 A d E d t \ & E= _0 ; I_d= _0 A d d t ( _0 ) \ & I_d=A ( d d t )= constant aligned Also B due to I_d is max ^m at surface of imaginary cylinder

Question 5

The electric field in a plane electromagnetic wave is given by E_z=60 (5 x +1.5 10^9 t ) V / m . Then expression for the corresponding magnetic field is (here subscripts denote the direction of the fi

Accepted Answer

aligned & v = k = 1.5 10^9 5 =3 10^8 ~m / s \ & B _0= F _0 v = 60 3 10^8 =20 10^ -8 =2 10^ -7 ~T aligned B _ y =2 10^ -7 (5 x +1.5 10^9 t ) T

Question 6

A parallel plate capacitor is charged by connecting it to a battery through a resistor. If I is the current in the circuit, then in the gap between the plates:

Accepted Answer

According to modified Ampere's law B . d l= _0 (I_C+I_D ) For Loop L_1 I_C 0 and I_D=0 For Loop L_2 I_C=0 and I_D 0 Due to KCL I_C=I_D

Question 7

The electromagnetic radiation which has the smallest wavelength are

Accepted Answer

Among the given options, -rays has the smallest wavelength.

Question 8

The property which is not of an electromagnetic wave travelling in free space is that:

Accepted Answer

The EM waves originate from an accelerating charge. The charge moving with uniform velocity produces steady state magnetic field.

Electromagnetic Waves — Previous Year Questions & Solutions