Electricity and magnetism

Question 1

What is needed for an electrical current to flow in a circuit?

Answer 1

A source of energy, eg. a battery, and a complete path for electrons to flow

Question 2

What is the SI unit for electrical charge, and how is it calculated?

Answer 2

The SI unit for electrical charge is the coulomb (C), calculated as Charge = Current × Time.

Question 3

What creates a magnetic field around a magnet?

Answer 3

A magnetic field is generated by the alignment of atomic dipoles within a material, and its strength can be visualised with iron filings.

Question 4

Potential

Answer 4

Potential is the amount of work needed per unit of charge to move it in an electric field, measured in volts (V).

Question 5

What is the difference between conductors and insulators?

Answer 5

Conductors allow electric charges to flow freely and have low resistance (e.g., metals), while insulators do not allow charge to flow and have high resistance (e.g., rubber).

Question 6

How does a solenoid strengthen its magnetic effect?

Answer 6

By winding a conductor into a coil, each turn reinforces the magnetic field, and inserting a ferromagnetic core (e.g., soft iron) amplifies this effect.

Question 7

What is a practical use of electromagnets in medical imaging?

Answer 7

Electromagnets are used in CT scanners to alter the focal spot during x-ray production.

Question 8

What does Faraday’s law of induction state?

Answer 8

The magnitude of the induced electromotive force (EMF) in a conductor is directly proportional to the rate of change of magnetic flux through the circuit