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Course: Alhussan Physics — Stage 8
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Curriculum

Alhussan Physics — Stage 8

Chapter 6: Forces, Motion and Pressure

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Chapter 7: Light

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Chapter 8: Magnetism and Electromagnets

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Chapter 9: Energy Resources

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Chapter 10: The Earth in Space (Galaxies and Asteroids)

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Quiz

8.4 Using electromagnets — Quiz

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  • Questions count: 10
  • Passing grade: B+
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1.
Which term matches this definition? “A switch operated by an electromagnet, so a small current controls a large one.”
Diode
Cell
Fuse
Relay
2.
Why does a car use a relay for the starter motor?
Batteries need it
It makes sound
The starter takes a dangerously high current
It is cheaper
3.
How does an electromagnetic door holder help in a fire?
It locks the door
It sprays water
It opens all doors
The alarm cuts the current and the door closes
4.
True or false? In a reed relay, the reeds are magnetised and touch to complete the second circuit.
True
False
5.
Radiographers use a relay so they can switch X-ray machines from a safe ____.
height
colour
temperature
distance
6.
True or false? An electric bell works without an electromagnet.
True
False
7.
The flow diagram shows a relay. What happens at "?"
Dr Dabour Hub Academy - figure 1
The motor switches off
The battery recharges
The coil melts
Reeds attract and touch, closing the second circuit
8.
A relay coil uses 0.2 A to switch a starter motor taking 200 A. How many times larger is the motor current?
1000 times
200 times
10,000 times
40 times
9.
A circuit breaker uses an electromagnet to:
Make light
Make current bigger
Break the circuit when current is too high
Store energy
10.
Why must the relay circuit carry only a small current?
It makes noise
It saves copper only
It is safer for the person switching
Small currents are faster
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Part of Chapter 8: Magnetism and Electromagnets — see every lesson and quiz in this unit.
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