Q. 7

An EM wave radiates outwards from a dipole antenna, with E₀ as the amplitude of its electric field vector. The electric field E₀ which transports significant energy from the source falls off as
A.

B.

C.

D. remains constant

Class 12th Physics - Exemplar 8. Electromagnetic Waves

Answer :

Given

Amplitude of electric field vector = E₀

Explanation:

We know that, the intensity of radiation is given,

Where W is the energy emitted by the bulb, t is the time, and A is the area on which the radiation is incident.

Therefore, assuming the energy and time to be constant we have,

An antennae radiates energy in a spherical shape around it, thus A=4πr².

We , know that the electric field and average intensity or energy are related as

Therefore, the energy from the source falls of as .

Rate this question :

How useful is this solution?

We strive to provide quality solutions. Please rate us to serve you better.

PREVIOUSThe ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is NEXTAn electromagnetic wave travels in vacuum along z direction : . Choose the correct options from the following:

RELATED QUESTIONS :

Which mode of propagation is used by short wave broadcast services ?

Physics - Board Papers

Which basic mode of communication is used in satellite communication? What type of wave propagation is used in this mode? Write, giving reason, the frequency range used in this mode of propagation.

Physics - Board Papers

(a) Why are infra-red waves often called heat waves ? Explain.

(b) What do you understand by the statement, ‘‘Electromagnetic waves transport momentum’’ ?

Physics - Board Papers

A laser beam has intensity 2.5 × 10¹⁴ W m^–2. Find the amplitudes of electric and magnetic fields in the beam.