Activity 3


Pair work AIM


Investigate what happens when electrical current passes through wire bent around a conductor.


HYPOTHESIS


Passing electric current through a wire coil around a metal object turns the metal into an electromagnet as long as the circuit is closed.


MATERIALS • three 1,5 V cells • a switch • connecting wires


• iron filings or pins


METHOD Step 1 Place the compass on a level surface and bring the magnet up to it. Observe what happens to the compass needle.


Step 2 Set up the circuit as shown and hold the wire above the compass. Observe what happens to the needle.


Step 3 Close the switch and hold the compass above the current carrying wire. Observe what happens to the needle.


Step 4 Wind the insulated copper wire around the iron nail.


Step 5 Bring it close to the iron filings or pins. Observe what happens.


Step 6 Connect the insulated copper wire to the circuit as shown in Figure 6.


Step 7 Close the switch and bring the nail close to the iron filings. What do you observe?


Step 8 Open the switch. What do you observe? RESULTS


Record your observations in a table.


QUESTIONS 1 Write a conclusion for this investigation. 2 Electromagnets are used in metal scrap yards. Interpret the findings of this investigation to explain how they are used for this application.


Exam word


interpret – work out the meaning


Figure 6 An electromagnet


insulated copper wire


switch 1,5 V cell iron nail


• a magnetic compass • a magnet • an iron nail


• a piece of insulated copper wire with the insulation removed from both ends


Caution


Do not leave the current on for more than a few seconds as the battery will get flat very quickly.


Investigate the magnetic effect of a current in a wire coil


copper wire


Unit 3 Effects of an electric current 115


STRAND 3


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