KinexiaLEARN PHYSICS

Wave Period — Microwave Oven (Worked Example)

Medium
Problem

A microwave oven generates electromagnetic waves at 2.45 GHz. What is the period of one microwave oscillation?

Given

  • f = 2.45 GHz = 2.45 × 10⁹ Hz

Find

The period T.

Principle

T = 1/f works from ocean swells to microwaves — the reciprocal relationship is universal.

Formula

Solution

  1. Convert: f=2.45×109 Hzf = 2.45 \times 10^9\ \mathrm{Hz}

  2. Substitute: T=1/(2.45×109)T = 1/(2.45 \times 10^9)

  3. Calculate: T=4.08×10−10 s=0.408 nsT = 4.08 \times 10^{-10}\ \mathrm{s} = 0.408\ \mathrm{ns}

0.408 ns

Unit check

1 ÷ Hz = s — correct.

What this means physically

0.408 nanoseconds — the electric field flips direction 2.45 billion times per second, which is what torques water molecules back and forth and heats food.

Common mistake

Losing track of the giga prefix. 2.45 GHz = 2.45 × 10⁹ Hz — forgetting the 10⁹ gives an answer a billion times too large.