Q.23

Expert-verified
Found in: Page 452

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# Cell phone conversations are transmitted by high-frequency radio waves. Suppose the signal has wavelength 35 cm while traveling through air. What are the (a) frequency and (b) wavelength as the signal travels through 3-mm-thick window glass into your room?

Part (a) The frequency is Hz.

Part (b) The wavelength as the signal travels through 3-mm-thick window glass is 23.3 cm.

See the step by step solution

## Part (a) Step 1. Given information:

The wavelength of the signal travelling in air is

The speed of radio waves in air is

The refractive index of glass is

## Part (a) Step 2. Calculating the frequency when the radio waves travel in air:

Frequency is defined as the complete waves travelling per unit time.

The formula to calculate the frequency of the radio signal in terms of c is given by

Substitute and 0.35m for into the above formula to calculate the frequency.

## Part (b) Step 1. Calculating the frequency when the signal pass through the thick glass window:

The frequency is same in air as well as glass as it is the same source.

The velocity of the signal when travelling through the glass is given by

Substitute 1.5 for n and for c into the above formula to calculate the velocity.

The formula to calculate the wavelength of the signal is given by

Substitute for and for f into the above formula to calculate the wavelength of the signal through the glass window.