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Question 1
A student is investigating the properties of electromagnets. |
a) | Describe how a student could construct an electromagnet.
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b) | Describe two ways in which the student could make the electromagnet stronger.
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Question 2
A student constructs an electromagnet by wrapping a wire around a wooden rod. The student then connects the coil of wire to a D.C. power supply. |
a) | Explain what is meant by a D.C. power supply.
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b) | The student tests the strength of the electromagnet by picking up magnetic pins on the desk. The current is varied and the number of pins picked up is counted. The table below shows the student's data. Plot a graph of the student's results. Model answer
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c) | Describe the pattern shown by the student's results.
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d) | Describe two ways the student could increase the number of pins picked up at 1.2 A.
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e) | Describe how the number of pins picked up would vary if an A.C. power supply was used.
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Question 3
The diagram below shows a current carrying wire. |
a) | Explain a method the student could follow to identify the shape of the magnetic field around the wire.
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b) | Sketch the magnetic field pattern around the current carrying wire.
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c) | The student wraps the wire into a coil to form a solenoid. The diagram below shows the magnetic field around the solenoid. Which letter represents the North pole of the solenoid. B
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d) | State two ways in which the strength of the magnetic field could be increased.
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Question 4
Many buildings use electromagnets to keep doors open. In the event of a fire or when the button is pressed, the doors swing closed. |
a) | Explain how the electromagnet keeps the door open.
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b) | The image below shows the circuit diagram for the electromagnet. Describe what happens to the door when the switch is pressed.
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c) | The electromagnet on this door isn't strong enough to keep the door open. Describe two changes the manufacturer could make to the electromagnet to make it stronger.
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Question 5
Electromagnets are used at recycling centres to sort materials. |
a) | Describe the construction of an electromagnet.
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b) | The table below lists some of the metals to be sorted. Tick all the materials that would be picked up by the electromagnet.
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c) | Describe how the strength of the electromagnet could be increased to pick up larger items.
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Question 6
a) | Which of the following would increase the strength of an electromagnet. A use an A.C. power supply B increase the number of turns on the coil C use a strong core such as concrete D decrease the current through the electromagnet
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b) | State one advantage of using an electromagnet over a bar magnet.
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c) | A student wants to construct an electromagnet. Sketch out the construction of an electromagnet.
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Question 7
This question is about an electric bell. |
a) | Describe what happens when the switch is pressed.
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b) | The electromagnet isn't strong enough to attract the hammer. Describe how the student could modify the electromagnet to make it stronger.
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Question 8
A student is investigating how strength of an electromagnet varies with the number of turns. The student's method is below.
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a) | State the independent variable in the student's investigation.
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b) | State two control variables for the student's experiment.
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c) | The student plots a graph of number of turns against number of pins picked up. Describe the relationship between number of turns and number of pins picked up.
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d) | Why is it important to keep the current flowing through the electromagnet fixed during each trial.
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