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Q.1. Match List-I with List-II (2022)
(1) (a) - (iii), (b) - (ii), (c) - (i), (d) - (iv)
(2) (a) - (iii), (b) - (iv), (c) - (ii), (d) - (i)
(3) (a) - (ii), (b) - (iii), (c) - (iv), (d) - (i)
(4) (a) - (iv), (b) - (iii), (c) - (ii), (d) - (i)
|AM radio waves||102 m|
|Infrared radiations||10–4 m|
(a) - (ii) (b) - (iii) (c) - (iv) (d) - (i)
Q.2. When light propagates through a material medium of relative permittivity εr and relative permeability εr, the velocity of light μr, v is given by (c-velocity of light in vacuum) (2022)
Q.3. For a plane electromagnetic wave propagating in the x-direction, which one of the following combinations gives the correct possible directions for the electric field (E) and magnetic field (B) respectively? (2021)
Q.4. A capacitor of capacitance 'C' is connected across an ac source of voltage V, given by The displacement current between the plates of the capacitor would then be given by: (2021)
Q.5. The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is : (c = speed of electromagnetic waves) (2020)
A: 1 : c
B: 1 : c2
C: c : 1
D: 1 : 1
Energy distribution is same so ration of electric field and magnetic field will be 1 : 1
Q.6. Which colour of the light has the longest wavelength? (2019)
Red has the longest wavelength among the given options.
Q.7. An em wave is propagating in a medium with a velocityThe instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along :- (2018)
A: –z direction
B: +z direction
C: –y direction
D: –x direction
(Therefore, electric field vector is along + y axis)
i.e., direction of magnetic filed vector is along + z direction.
Q.8. In an electromagnetic wave in free space the root mean square value of the electric field is Erms = 6V/m. The peak value of the magnetic field is :- (2017)
A: 2.83 × 10–8 T
B: 0.70 × 10–8 T
C: 4.23 × 10–8 T
D: 1.41 × 10–8 T
Q.9. Out of the following options which one can be used to produce a propagating electromagnetic wave ? (2016)
A: An accelerating charge
B: A charge moving at constant velocity
C: A stationary charge
D: A charge less particle
An electric charge at rest has electric field in the region around it, but magnetic field is absent. A moving charge produces both electric and magnetic field. When a charge is moving with constant velocity, electric and magnetic field will not change with time. Therefore, no electromagnetic wave will be produced.
But, if the charge is moving with non-zero acceleration, electric and magnetic field will change with space and time. Electromagnetic waves will be produced.
Therefore, accelerated charge emits electromagnetic waves.