Lesson T5.3.3
T5.3.3 Electromagnets and D.C. motors Quiz: KS3 Physics, Unit 5
20 questions
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Lesson T5.3.3, Electromagnets and D.C. motors: 20 multiple choice questions for the KS3 Physics (National Curriculum), Unit 5: Electricity and magnetism, written with Revision Ninja.
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The 20 questions
-
What is produced around any wire carrying an electric current?
- A sound wave
- A magnetic field
- A gravitational wave
- A static charge
-
What is the scientific term for a cylindrical coil of wire carrying an electric current?
- Solenoid
- Resistor
- Capacitor
- Transformer
-
What component is placed inside a coil to make an electromagnet much stronger?
- Plastic rod
- Glass tube
- Iron core
- Copper ring
-
Which change increases the strength of an electromagnet?
- Increasing resistance
- Lowering the voltage
- Lengthening the wires
- Increasing the current
-
What is a key advantage of an electromagnet over a permanent magnet?
- Can be switched off
- Always magnetic
- Lighter weight
- Cheaper metal
-
Which of these is a common use of an electromagnet?
- A plastic ruler
- A compass needle
- An electric bell
- A glass lens
-
What is the main energy transfer function of a DC electric motor?
- Chemical to thermal
- Thermal to light
- Electrical to kinetic
- Kinetic to electrical
-
Why does a current-carrying wire in a magnetic field experience force?
- Gravity pulls sideways
- Air pushes electrons
- Wire becomes hot
- Magnetic fields interact
-
What happens to a current-carrying coil placed inside a magnetic field?
- It charges up
- It vibrates vertically
- It rotates
- It melts
-
What component reverses the current every half turn in a DC motor?
- Step-down transformer
- Carbon brush
- Split-ring commutator
- Rheostat
-
Which action reverses the direction of rotation in a DC motor?
- Adding more turns
- Removing the brushes
- Reversing current direction
- Shortening the coil
-
Which change makes a DC motor spin faster?
- Decreased current
- Increased current
- Thinner wire
- Shorter coil
-
What happens to an electromagnet field when current is switched off?
- Field stays strong
- Field reverses
- Field disappears
- Field doubles
-
What is the main function of an electrical relay?
- Increase resistance
- Switch larger circuits
- Store electrical charge
- Generate AC power
-
Which part of a simple DC motor is a coil of wire?
- The switch
- The commutator
- The battery
- The armature
-
A solenoid has a magnetic field much like which object?
- A bar magnet
- A resistor
- A lens
- A battery
-
Why does adding more turns of wire strengthen an electromagnet?
- Voltage increases
- Current stops
- Magnetic fields combine
- Resistance decreases
-
What is the role of the permanent magnet in a DC motor?
- Reverse the voltage
- Provide magnetic field
- Reduce friction
- Generate electrical power
-
Which change reduces the strength of a DC motor?
- Stronger magnet
- More turns
- Faster spin
- Smaller current
-
Why is the magnetic field around a current-carrying wire temporary?
- Atoms decay
- Battery discharges
- Depends on current
- Wire melts fast
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