Electromagnetism questions

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Electromagnetism question collection

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

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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

What happens to an induced magnet when the field is removed?
  1. It loses most of its magnetism
  2. It keeps all of its magnetism
  3. Its north and south poles exchange places
  4. It becomes electrically charged

Question 3

What happens to the force on a current-carrying wire if the magnetic field strength doubles?
  1. It doubles
  2. It halves
  3. It stays the same
  4. It becomes zero

Question 4

In Fleming's left-hand rule, what direction does the thumb show?
  1. Force
  2. Current
  3. Magnetic field
  4. Induced current

Question 5

A magnet is moved into a coil. What happens to the induced current if its motion is reversed?
  1. It reverses
  2. It doubles
  3. It stays unchanged
  4. It becomes direct current

Question 6

What happens to the induced voltage when a magnet moves faster through a coil?
  1. It increases
  2. It decreases
  3. It stays the same
  4. It falls to zero

Question 7

Which setup can demonstrate electromagnetic induction?
  1. A moving magnet through a coil connected to a voltmeter
  2. A stationary magnet inside a stationary coil and voltmeter
  3. A coil and voltmeter with no magnetic field
  4. A moving magnet beside a disconnected coil

Question 8

Which current does an alternator produce?
  1. Alternating current
  2. Direct current
  3. Pulsating direct current
  4. No current without a battery

Question 9

What is the force on a current-carrying wire in a magnetic field called?
  1. Motor effect
  2. Generator effect
  3. Electrostatic induction
  4. Electromagnetic induction

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 alternating potential difference using a turns ratio
  2. Converts alternating current into direct current
  3. Stores electrical charge between two plates
  4. Changes resistance when its temperature changes

Question 13

For the same power, what happens to the secondary current in a step-up transformer?
  1. It decreases
  2. It increases
  3. It falls to zero
  4. It stays the same

Question 14

How is a simple electromagnet made?
  1. Pass current through a coil wrapped around an iron core
  2. Connect a coil wrapped around a plastic rod to a cell
  3. Wrap a coil around an iron core but leave it disconnected
  4. Place a permanent magnet next to a coil of wire

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 outside the magnet
  3. North to south both inside and outside
  4. From the centre towards both poles

Question 17

Which pattern of field is produced by a current through a straight wire?
  1. Concentric circles around the wire
  2. Radial lines pointing outwards
  3. A spiral into the wire
  4. Parallel straight lines

Question 18

What does a moving-coil microphone produce from sound pressure variations?
  1. Variations in electric current
  2. A constant electric current
  3. A permanent magnetic field
  4. A steady mechanical force

Question 19

Which current produces a steady magnetic field in a solenoid?
  1. Direct current
  2. Alternating current
  3. Pulsed light
  4. Static charge

Question 20

What does a loudspeaker produce from variations in electric current?
  1. Variations in sound pressure
  2. A constant sound pressure
  3. A permanent electric charge
  4. A steady magnetic field

Question 21

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

Question 22

What happens to an alternator's induced potential difference every half turn?
  1. It reverses
  2. It falls to zero
  3. It increases
  4. It stays constant

Question 23

Which supply is needed for a transformer to operate continuously?
  1. Alternating current
  2. Direct current
  3. Static charge
  4. Pulsed light

Question 24

Which device shows the direction of a magnetic field at one point?
  1. A plotting compass
  2. Iron filings
  3. A steel paperclip
  4. A voltmeter

Question 25

What happens to the induced emf if a coil rotates faster through a magnetic field?
  1. The induced emf increases
  2. The induced emf decreases
  3. The induced emf remains zero
  4. The induced emf stays the same

Question 26

For the same coil motion, which change increases the induced voltage?
  1. Use a stronger magnet
  2. Use a weaker magnet
  3. Use fewer turns on the coil
  4. Hold the magnet stationary inside the coil

Question 27

What is the transformer equation?
  1. \(\frac{V_p}{V_s}=\frac{N_p}{N_s}\)
  2. \(V_pV_s=N_p+N_s\)
  3. \(\frac{V_p}{V_s}=\frac{N_s}{N_p^2}\)
  4. \(V_p+V_s=\frac{N_p}{N_s}\)

Question 28

A transformer has more turns on its secondary coil. What type is it?
  1. Step-up transformer
  2. Step-down transformer
  3. Rectifier
  4. Thermistor

Question 29

What is the role of the split-ring commutator in a DC motor?
  1. It reverses the current every half-turn
  2. It increases the supply potential difference
  3. It removes the magnetic field
  4. It measures the motor’s resistance

Question 30

Why is the core of an electromagnet made from soft iron?
  1. It magnetises and demagnetises easily
  2. It retains its magnetism strongly after current stops
  3. It has a particularly low density
  4. It blocks current from flowing through the coil

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

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