GCSE Physics revision

Properties of electromagnetic waves 2

Electromagnetic waves

AQA 4.6.2.3

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AQA student objectives

Learning pathway

ALL 🎯

Draw conclusions from given data about the risks and consequences of exposure to radiation.

MOST 🎯🎯

Interpret results or representations related to properties of electromagnetic waves 2.

SOME 🎯🎯🎯

Analyse an unfamiliar problem involving properties of electromagnetic waves 2 and justify the method or conclusion.

Revision summary

Read on screen, then print for Cornell-style active revision.

Radio waves can be produced by oscillating electric circuits that carry an alternating current (AC).
The frequency of the radio waves produced matches the frequency of the alternating current — for example, mains AC at 50 Hz produces radio waves at 50 Hz.
This means we can deliberately generate radio waves of a specific frequency by controlling the AC supply.

1. Creating Radio Waves from Alternating CurrentAQA

Radio waves can be produced by oscillating electric circuits that carry an alternating current (AC).
The frequency of the radio waves produced matches the frequency of the alternating current — for example, mains AC at 50 Hz produces radio waves at 50 Hz.
This means we can deliberately generate radio waves of a specific frequency by controlling the AC supply.

When a conductor (such as a car or radio aerial) absorbs incoming radio waves, an alternating current is induced within it.
The induced alternating current has the same frequency as the incoming radio waves.
This is the principle behind how radio aerials work — converting electromagnetic wave energy back into an electrical signal.

2. Detecting Radio Waves with a ConductorAQA

When a conductor (such as a car or radio aerial) absorbs incoming radio waves, an alternating current is induced within it.
The induced alternating current has the same frequency as the incoming radio waves.
This is the principle behind how radio aerials work — converting electromagnetic wave energy back into an electrical signal.

Electrons can absorb electromagnetic radiation to gain energy and move to a higher energy level shell, further from the nucleus.
When an electron drops from a higher energy level to a lower one (closer to the nucleus), it emits electromagnetic radiation.
This emission of light is the principle behind street lights — electrons are excited to higher energy states and then release light as they fall back down.
Since light is part of the electromagnetic spectrum, this process is a natural source of electromagnetic radiation.

3. Electron Energy Level Transitions and Light EmissionAQA

Electrons can absorb electromagnetic radiation to gain energy and move to a higher energy level shell, further from the nucleus.
When an electron drops from a higher energy level to a lower one (closer to the nucleus), it emits electromagnetic radiation.
This emission of light is the principle behind street lights — electrons are excited to higher energy states and then release light as they fall back down.
Since light is part of the electromagnetic spectrum, this process is a natural source of electromagnetic radiation.

Ultraviolet (UV) radiation, X-rays, and gamma rays are all classified as ionising radiation because they carry enough energy to damage living cells.
Ionising radiation can cause damage to DNA, leading to mutations that increase the risk of cancer.
The level of radiation danger is measured in sieverts (Sv), where 1 millisievert (mSv) is equal to 1 / 1000 of a sievert.

4. Ionising Radiation and Health HazardsAQA

Ultraviolet (UV) radiation, X-rays, and gamma rays are all classified as ionising radiation because they carry enough energy to damage living cells.
Ionising radiation can cause damage to DNA, leading to mutations that increase the risk of cancer.
The level of radiation danger is measured in sieverts (Sv), where 1 millisievert (mSv) is equal to 1 / 1000 of a sievert.