Edexcel GCSE Physics (1PH0) — Light and the electromagnetic spectrum
Where:
A transmitter operates with an alternating current frequency of . Calculate the wavelength of the radio waves produced. (Speed of electromagnetic waves in air = )
Step 1: Identify the values and convert units.
Step 2: Rearrange the wave equation to make wavelength the subject.
Step 3: Substitute the values and calculate.
| Wave Type | How it is produced |
|---|---|
| Radio waves | Produced by intentional oscillations in electrical circuits. |
| Gamma rays | Produced spontaneously by changes in the nucleus of an atom. |
Students often state that radio waves are produced by 'vibrations' — you must use the specific Edexcel mark scheme phrases 'oscillating charges' or 'oscillations in electrical circuits' to earn the mark.
Always state the 'same frequency' rule: explicitly write that the frequency of the alternating current in the transmitter, the radio wave itself, and the induced current in the receiver are all exactly equal.
Remember that radio waves transfer energy and information, not matter — the electrons stay in their respective aerials and do not physically travel between the transmitter and receiver.
In comparison questions, contrast the origin of the waves: radio waves come from electrical circuits, whereas gamma rays are produced by changes within the nucleus of an atom.
Alternating current (AC)
An electric current that continuously reverses its direction and changes its magnitude in a cyclical manner.
Oscillation
A repetitive back-and-forth motion; in a circuit, it refers to the cyclical movement of electrons.
Oscillating charges
Electrons moving rapidly back and forth in a conductor, which generates radio waves.
Transmitter
A device or circuit that generates and emits radio waves using a high-frequency AC source.
Receiver
A device or circuit that absorbs radio waves, causing its electrons to oscillate and inducing an electrical signal.
Aerial
A metal conductor (antenna) used to either transmit radio waves into the air or receive them.
Induced current
The flow of charge created in a conductor when it is exposed to the changing electromagnetic fields of a radio wave.
Put your knowledge into practice — try past paper questions for Physics
Alternating current (AC)
An electric current that continuously reverses its direction and changes its magnitude in a cyclical manner.
Oscillation
A repetitive back-and-forth motion; in a circuit, it refers to the cyclical movement of electrons.
Oscillating charges
Electrons moving rapidly back and forth in a conductor, which generates radio waves.
Transmitter
A device or circuit that generates and emits radio waves using a high-frequency AC source.
Receiver
A device or circuit that absorbs radio waves, causing its electrons to oscillate and inducing an electrical signal.
Aerial
A metal conductor (antenna) used to either transmit radio waves into the air or receive them.
Induced current
The flow of charge created in a conductor when it is exposed to the changing electromagnetic fields of a radio wave.
