Electromagnetism questions

By Interwoven Maths

Electromagnetism question collection

Review Electromagnetism questions for Physics, with correct answers shown and coverage across magnetic fields; electromagnets; motor and generator effects.

Back to Electromagnetism practice Back to Physics

Question 1

What is the direction of the magnetic field around a current-carrying wire determined by?
  1. Right-hand rule
  2. Left-hand rule
  3. Faraday's law
  4. Ohm's law

Question 2

Which equation gives magnetic flux?
  1. \(\Phi = BA\cos\theta\)
  2. \(\Phi = B + A\)
  3. \(\Phi = B/A\)
  4. \(\Phi = B + \cos\theta\)

Question 3

If area is \(0.2\,\mathrm{m^2}\), field \(0.5\,\mathrm{T}\), and angle \(60^\circ\), what is the magnetic flux?
  1. \(0.05\,\mathrm{Wb}\)
  2. \(0.1\,\mathrm{Wb}\)
  3. \(0.05\,\mathrm{T}\)
  4. \(0.2\,\mathrm{Wb}\)

Question 4

Which law explains induced emf and current when flux changes?
  1. Faraday's law
  2. Ohm's law
  3. Hooke's law
  4. Newton's third law

Question 5

According to Lenz's law, what will the induced current always do?
  1. Oppose the change in magnetic flux
  2. Increase flux
  3. Delayed by one second
  4. Stop magnetic field

Question 6

How can the induced voltage in a coil be increased?
  1. Move magnet faster or use more turns
  2. Use fewer turns
  3. Slow the magnet
  4. Keep field constant

Question 7

Which piece of equipment demonstrates magnetic flux linkage changing?
  1. Moving magnet through coil connected to voltmeter
  2. Static dust particle
  3. Fixed magnet and coil
  4. DC battery alone

Question 8

What is the unit of magnetic flux?
  1. Weber (Wb)
  2. Tesla
  3. Volt
  4. Ohm

Question 9

Which force acts on a wire carrying current in a magnetic field?
  1. Motor effect force
  2. Gravitational force
  3. Centripetal force
  4. Buoyant force

Question 10

Which equation gives the force on a current-carrying wire?
  1. \(F = BIl\)
  2. \(F = B + I + l\)
  3. \(F = \frac{BI}{l}\)
  4. \(F = BI^2\)

Question 11

A coil \(0.3\,\mathrm{m}\) long carries \(2\,\mathrm{A}\) in a \(0.2\,\mathrm{T}\) field. What is the force?
  1. \(0.12\,\mathrm{N}\)
  2. \(0.03\,\mathrm{N}\)
  3. \(1.2\,\mathrm{N}\)
  4. \(0.6\,\mathrm{N}\)

Question 12

What does a transformer do to alternating voltage?
  1. Changes voltage via coil turns ratio
  2. Converts AC to DC
  3. Creates magnetic monopoles
  4. Stops current

Question 13

What happens to current in a step-up transformer?
  1. Lower for the same power
  2. Higher
  3. Zero
  4. Unchanged

Question 14

Describe how an electromagnet is made?
  1. Current through coil around iron core
  2. Permanent magnet wrapped in wire
  3. Electric heating element
  4. Chemical battery

Question 15

Which device uses induced current to heat metals without contact?
  1. Induction cooker
  2. Electrostatic speaker
  3. Thermistor
  4. Solar panel

Question 16

Magnetic field lines show direction from where to where?
  1. North to south outside the magnet
  2. South to north inside
  3. In random directions
  4. Towards the equator

Question 17

Which pattern of field is produced by current through straight wire?
  1. Concentric circles around wire
  2. Radial lines outward
  3. Spiral into wire
  4. Parallel straight lines

Question 18

Which instrument measures the magnetic field strength?
  1. Hall probe
  2. Voltmeter
  3. Thermistor
  4. Ruler

Question 19

What type of current magnetises a solenoid?
  1. Direct current
  2. Alternating current
  3. Pulsed light
  4. Static charge

Question 20

A conductor moves through a magnetic field, cutting \(0.15\,\mathrm{Wb}\) in \(0.05\,\mathrm{s}\). What is the induced emf?
  1. \(3\,\mathrm{V}\)
  2. \(0.75\,\mathrm{V}\)
  3. \(15\,\mathrm{V}\)
  4. \(0.3\,\mathrm{V}\)

Question 21

Which quantity is measured in tesla?
  1. Magnetic field strength
  2. Electric potential
  3. Resistance
  4. Power

Question 22

Why does a coil with more turns produce higher induced emf?
  1. More flux lines are cut per revolution
  2. Turns reduce flux
  3. Current halts
  4. Resistance zero

Question 23

Transformers only work with what type of current?
  1. Alternating current
  2. Direct current
  3. Static current
  4. Pulsed light

Question 24

Which tool shows field direction around a bar magnet?
  1. Iron filings
  2. Voltmeter
  3. Hydrometer
  4. Ruler

Question 25

What happens to induced emf if coil rotates faster through magnetic field?
  1. Emf increases
  2. Emf decreases
  3. Emf stays zero
  4. Nothing changes

Question 26

Which change increases the induced voltage in a coil moving through a magnetic field?
  1. Move the magnet more rapidly so the magnetic flux changes faster.
  2. Use a magnet with a weaker field strength.
  3. Move the magnet more slowly.
  4. Replace the coil with thicker wire of the same length.

About this topic

Review Electromagnetism questions for Physics, with correct answers shown and coverage across magnetic fields; electromagnets; motor and generator effects.

This topic covers

Example question types