NEETPhysicsMagnetic Properties of Matter
An electromagnetic wave is propagating through a medium with relative permeability 1 and relative permittivity 4 . If the average intensity of the wave is 540 W/m ^2 , what is the rms value of the electric field of the wave? (Given ₀ ₀ = 120 , )
Options
- A360 V/m
- B180 V/m
- C180 2 V/m
- D3 V/m
Correct answer
B. 180 V/m
Step-by-step solution
First, find the wave impedance ( Z ) of the medium, which is the ratio of the electric field to the magnetic field ( E/H ): Z = = ₀ _r ₀ _r Z = ₀ ₀ _r _r Substitute the given values: Z = 120 1 4 = 120 1 2 = 60 , The average intensity ( I ) of an electromagnetic wave is related to the rms electric field ( E_ rms ) and the wave impedance ( Z ) by the formula: I = E_ rms ^2 Z Substitute the known values of intensity and impedance: 540 = E_ rms ^2 60 Multiply both sides by 60 : E_ rms ^2 = 540 60 E_ rms ^2 = 32400 Taki