Question

The ratio of amplitude of electric field to the amplitude of the magnetic field associated with an electromagnetic wave propagating in glass (n = 1.5) is ______.

Options

• 3 × 10⁸ ms⁻¹

• 2 × 10⁸ ms⁻¹

• 3.3 × 10⁻⁹ ms⁻¹

• 5 × 10⁻⁹ ms⁻¹

Answer 1

The ratio of amplitude of electric field to the amplitude of the magnetic field associated with an electromagnetic wave propagating in glass (n = 1.5) is 2 × 10⁸ ms⁻¹.

Explanation:

In any electromagnetic wave, the ratio of the amplitude of the electric field (E₀) to the amplitude of the magnetic field (B₀) is equal to the speed of the wave in that medium.

Speed of light in a medium v = `E_0/B_0 = c/n`

Where: 

speed of light in vacuum (c) = 3 × 108 m/s 

refractive index of the medium (n) = 1.5

Substitute the values:

`E_0/B_0 = (3 xx 10^8)/1.5`

= 2 × 10⁸ m/s

∴ The ratio is 2 × 10⁸ ms⁻¹.