What is frequency?

Frequency is how many times something repeats in one second. In science we count the number of cycles (or repeats) of a wave, vibration, or signal that happen each second. The unit we use is called Hertz (Hz), where 1 Hz means one cycle per second.

Let's break it down

Imagine you’re pushing a child on a swing. Each time the swing goes forward and back is one cycle. If you can push the swing so it completes 2 cycles every second, the swing’s frequency is 2 Hz. The time it takes for one full cycle is called the period (T). Frequency (f) and period are linked by the simple formula: f = 1⁄T. So a fast swing (short period) has a high frequency, and a slow swing (long period) has a low frequency.

Why does it matter?

Frequency tells us the pitch of a sound (high frequency = high pitch), the color of light (different frequencies make red, green, blue, etc.), and how fast a computer’s processor works (higher clock frequency means more operations per second). It also determines how far radio waves can travel and how much data we can send over Wi‑Fi or cellular networks.

Where is it used?

  • Audio: musical notes, speaker output, microphone input.
  • Radio & TV: broadcasting stations use specific frequencies so receivers can tune in.
  • Wi‑Fi & Bluetooth: operate on 2.4 GHz or 5 GHz bands.
  • Mobile phones: use many frequency bands for 4G/5G.
  • Computer processors: measured in gigahertz (GHz).
  • Medical imaging: MRI machines use radio‑frequency waves.
  • Everyday appliances: microwave ovens use 2.45 GHz to heat food.

Good things about it

  • Enables clear communication: different frequencies let many signals coexist without mixing.
  • Provides precise timing: clocks and processors rely on stable frequencies for accurate operation.
  • Allows us to sense the world: our ears and eyes detect frequency changes to interpret sound and light.
  • Supports high‑speed data transfer: higher frequencies can carry more information per second.

Not-so-good things

  • Interference: when two signals use similar frequencies, they can clash and cause noise.
  • Limited range: very high frequencies (like millimeter‑wave 5G) don’t travel far and are blocked by obstacles.
  • Energy consumption: higher‑frequency processors often need more power and generate more heat.
  • Health concerns: prolonged exposure to strong high‑frequency electromagnetic fields can be harmful, so regulations are needed.