Electromagnetic spectrum Flashcards – Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028)

What is the electromagnetic spectrum?

The complete range of electromagnetic waves, arranged by frequency or wavelength.

What are the seven main regions of the electromagnetic spectrum in order of increasing frequency?

Radio waves → microwaves → infrared → visible light → ultraviolet → X-rays → gamma rays.

What is the speed of electromagnetic waves in a vacuum?

Approximately $3.0 \times 10^8\ \text{m/s}$.

What equation relates electromagnetic wave speed $c$, frequency $f$ and wavelength $\lambda$?

$c = f\lambda$

How are the frequency and wavelength of electromagnetic waves related in a vacuum?

Higher frequency corresponds to shorter wavelength.

What two types of broadcast signals are transmitted using radio waves?

Radio and television signals.

How does radio astronomy use radio waves to investigate objects in space?

It uses radio waves received from those objects.

How does radio frequency identification (RFID) use radio waves to identify objects?

It exchanges information with tags attached to the objects.

What are microwaves used for in mobile phone communication?

To carry signals.

How do microwaves heat food in a microwave oven?

They transfer energy to the food, raising its temperature.

How can excessive exposure to microwaves harm the body?

It can heat body cells internally.

How does infrared radiation transfer energy in an electric grill?

By heating.

What effect can excessive infrared exposure have on skin?

It can cause skin burns.

What device uses infrared for short-range communication?

A television remote controller.

What security application uses infrared radiation?

Intruder alarms.

How does thermal imaging use infrared radiation?

It detects infrared from objects to produce images related to their temperatures.

How can optical fibres carry information using infrared?

By carrying infrared signals.

What is visible light?

The region of the electromagnetic spectrum detected by the human eye, enabling vision.

How is visible light used in photography?

It is recorded to produce an image.

How is visible light used in illumination?

Light from a source makes a scene visible.

How is ultraviolet radiation used to detect fake banknotes?

It makes certain security marks visible.

How does ultraviolet radiation sterilise water?

By damaging microorganisms.

What can excessive ultraviolet exposure do to skin?

It can damage surface cells, potentially leading to skin cancer.

What can excessive ultraviolet exposure do to the eyes?

It can damage the eyes, potentially leading to eye conditions.

What are two uses of X-rays in scanning?

Medical scanning and security scanning.

Why can X-rays form an image of the body or a scanned object?

Different materials transmit different amounts of X-ray radiation.

What are two possible effects of excessive X-ray exposure on the body?

Cell damage and mutations.

How do gamma rays sterilise food and medical equipment?

They damage microorganisms.

How can gamma radiation help locate cancer?

It can be detected to help locate the cancer.

How is gamma radiation used to treat cancer?

It damages or destroys cancer cells.

What effect can excessive gamma radiation exposure have on healthy cells?

It can damage them.

Besides damaging healthy cells, what harm can excessive gamma radiation exposure cause?

It can cause mutations.

What type of electromagnetic wave is mainly used to carry signals between Earth and artificial satellites?

Microwaves.

What is a geostationary satellite?

A satellite that orbits so that it remains above the same point on Earth’s surface.

What two types of satellite orbit are used by satellite phones?

Low orbit and geostationary orbit.

What type of satellite is used for direct broadcast satellite television?

A geostationary satellite.