NEET UG PHYSICS MCQ: ELECTROMAGNETIC WAVES

1 Hard

1 of 1

Application +4 | -1

Calculate the electric and magnetic fields produced by the radiation coming from a 100 watt bulb at a distance of

3 \mathrm{~m}

. Assume that the efficiency of the bulb is

2.5 \%

and it is a point source.

View answer and explanation

Correct option: A

2.9 \mathrm{~Vm}^{-1}, 1.4 \times 10^{-7} \mathrm{~T}

Option A (

2.9 \mathrm{~Vm}^{-1}, 1.4 \times 10^{-7} \mathrm{~T}

) is correct because it is calculated using the efficiency of the bulb to find the power radiated, then using that power to find the intensity, and finally the electric and magnetic fields.

More Questions from ELECTROMAGNETIC WAVES

Practice All Chapter MCQs →

What is order of energy of X-rays (

{E_X}

), radio waves (

{E_R}

) and microwave (

{E_M}

)? The amplitude of the sinusoidally oscillating electric field of plane wave is

60\,\,\frac{V}{m}

. Then the amplitude of the magnetic field is An EM wave from air enters a medium. The electric fields are

{E_1} = {E_{01}}\hat x\cos \left[ {2\pi v\left( {\frac{z}{c} - t} \right)} \right]

in air and

{E_2} = {E_{02}}\hat x\cos \left[ {k\left( {2z - ct} \right)} \right]

in medium, where the wave number k and frequency ν refer to their values in air. The medium is non-magnetic.
If

{\varepsilon _{{r_1}}}

and

{\varepsilon _{{r_2}}}

refer to relative permittivities of air and medium respectively, which of the following options is correct? Electric field in a plane electromagnetic wave is given by

E = 50\sin \,(500x - 10 \times {10^{10}}t)\,v/m.

The velocity of electromagnetic wave in this medium is
(Given,

c

= speed of light in vacuum) If an electromagnetic wave is propagation in a medium with permeability 

\mathrm{\varepsilon }

and permittivity

\mathrm{\mu }

, then

\sqrt {\frac{\mathrm{\mu }}{\mathrm{\varepsilon }}}

is the In an E.M. wave the average energy density is associated with:-