Question

A wave is incident at an angle of 30°, from air to Teflon. Find the angle of transmission. Given, \(\epsilon_r\) = 2.1, \(\mu_1 = \mu_2\)

• A. 60.19°
• B. 39.47°
• C. 30°
• D. 20.18°

Hint:

Remember Snell's Law, \( n_1 \sin \theta_i = n_2 \sin \theta_t \) which relates angles of incidence and transmission to the refractive indices of media.

Answer 1

The Correct Option is D

Step 1: We are given that a wave is incident at an angle of \( \theta_i = 30^\circ \), from air to Teflon. The relative permittivity \( \epsilon_r = 2.1 \). The refractive index of air \( n_1 \) is approximately 1. The refractive index of Teflon is given by: \[ n_2 = \sqrt{\epsilon_r} = \sqrt{2.1} \approx 1.449 \] Step 2: Using Snell's Law, which states \( n_1 \sin \theta_i = n_2 \sin \theta_t \): \[ 1 \times \sin(30^\circ) = 1.449 \times \sin(\theta_t) \] \[ \sin(\theta_t) = \frac{\sin(30^\circ)}{1.449} = \frac{0.5}{1.449} = 0.345 \] Step 3: Calculate the transmission angle \[ \theta_t = \arcsin(0.345) = 20.18^\circ \] Therefore the angle of transmission is 20.18°.