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4.5.1. Electromagnetic induction
A subsection of Physics, 5054, through 4. Electricity and magnetism
Listing 10 of 19 questions
A simple apparatus used to demonstrate electromagnetic induction is shown in . S N magnet coil movement spring support LED The coil is connected to two light-emitting diodes (LEDs). The magnet moves into and out of the coil. Explain why there is an induced e.m.f. in the coil when the magnet moves. Explain why one LED lights up when the magnet moves into the coil and the other LED lights up when the magnet moves out of the coil. The LEDs are brighter when the magnet moves faster. Explain why.
5054_s15_qp_21
THEORY
2015
Paper 2, Variant 1
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Induced currents can be formed in a coil of wire by electromagnetic induction. Describe how to demonstrate the formation of an induced current in a coil of wire. Sketch and label a diagram of the arrangement of the apparatus. State two changes to the apparatus that increase the induced current. 1. 2. The direction of the induced current is determined by Lenz’s Law. 1. State Lenz’s Law. 2. Describe how Lenz’s Law applies in the experiment you described in . An electrical generator supplies power to a distant factory. The factory receives 500 kW of electrical power at a voltage of 33 kV. Calculate 1. the current in the wires supplying the power, current = 2. the electrical energy supplied to the factory in one hour. energy = The 33 kV voltage supplied to the factory is very high. Transmitting electrical energy at high voltage reduces energy losses in the transmission lines. Explain why.
5054_s16_qp_21
THEORY
2016
Paper 2, Variant 1
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shows two coils of insulated wire wound on an iron ring. Coil A is connected to a battery and a switch. The switch is open. Coil B is connected to a sensitive centre-zero voltmeter. centre-zero voltmeter open switch coil A iron ring coil B The switch is closed. There is a current in coil A. On , mark the direction of the current in coil A, draw the magnetic field lines produced in the iron ring. As the switch is closed, the voltmeter deflects to the right and then returns to zero. Explain why there is a deflection on the voltmeter. The switch is opened. State and explain what happens to the deflection on the voltmeter. Without changing coil A, state two changes to the apparatus that cause a greater deflection of the voltmeter. 1. 2. The battery in is replaced by an alternating current (a.c.) supply. The output from coil B is used to power a lamp that is a long distance away. Each lead from coil B to the lamp has a resistance of 2.5 Ω. These leads are represented by the two resistors shown in . lamp a.c. output from coil B 240 V, 1.6 A 2.5 Ω 2.5 Ω The output voltage of coil B is 240 V and the current in the circuit is 1.6 A. Calculate the electrical power produced by coil B. power = Calculate the total power loss in the leads to the lamp. power loss =
5054_s12_qp_22
THEORY
2012
Paper 2, Variant 2
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shows part of a torch. The torch does not contain a battery. S N magnet coil The torch is shaken and this causes the magnet to move backwards and forwards through the coil. Explain why an electromotive force (e.m.f.) is induced in the coil when the magnet moves. State one way to increase the e.m.f. induced. The current in the coil is used to produce light from a light-emitting diode (LED). In the space below, draw the circuit symbol for an LED. An LED is a more efficient source of light than a filament lamp. Explain what this statement means.
5054_s19_qp_21
THEORY
2019
Paper 2, Variant 1
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Questions Discovered
19