Topic 5.23–5.24: Electromagnetic waves, circuits, atoms and nuclei

How can radio waves be produced?

Oscillating electrical charges in an electrical circuit can produce radio waves.

How can radio waves induce oscillations in an electrical circuit?

An incoming radio wave induces an alternating electrical signal in a receiving aerial or circuit.

How are radio waves used to transmit information?

Information is encoded onto a signal by modulating its amplitude or frequency.

What changes in atoms can generate electromagnetic radiation?

Electrons changing energy levels can emit or absorb photons of particular energies.

What happens when an electron moves to a lower energy level?

It emits a photon whose energy equals the difference between the energy levels.

What happens when an atom absorbs a photon of suitable energy?

An electron may move to a higher energy level.

How can changes in nuclei generate electromagnetic radiation?

Changes in the energy of an atomic nucleus can produce gamma radiation.

What can happen when atoms absorb electromagnetic radiation?

Electrons may gain energy and move to higher energy levels, or the radiation may cause other changes depending on its energy.

What can happen when nuclei absorb electromagnetic radiation?

The nucleus may gain energy or undergo a nuclear change if the radiation has suitable energy.

What determines the frequency of a photon emitted by an atom?

The energy difference between the atomic energy levels; photon energy = Planck’s constant × frequency.

Why can atomic and nuclear changes generate different frequencies of radiation?

Different transitions involve different energy changes, producing photons with different frequencies.

What is the relationship between photon energy and frequency?

Photon energy is directly proportional to frequency.