4.2. Electrical quantities
A subsection of Physics, 5054, through 4. Electricity and magnetism
Listing 10 of 319 questions
11 A metal filament lamp is connected to a power supply. The electromotive force (e.m.f.) produced by the supply can be varied. is the circuit diagram. + – variable power supply metal filament lamp State what is meant by electromotive force (e.m.f.). Add appropriate circuit symbols to to show the position of an ammeter that measures the current in the circuit, a voltmeter that measures the voltage across the lamp. A student adds meters to the circuit and makes measurements of the current and voltage. He then plots the current/voltage graph shown in . 2.0 4.0 6.0 8.0 10.0 12.0 current / A voltage / V 0.5 1.0 1.5 2.0 Using values from , calculate the resistance of the lamp when the current is 0.70 A. Give your answer to an appropriate number of significant figures. resistance = State what, if anything, happens to the resistance of the lamp as the voltage increases. In normal use, the lamp is connected to a 12 V supply. Use to determine the power of the lamp when it is used in this way. power = When connected to a 12 V supply, thermionic emission occurs in the lamp. Describe what is meant by thermionic emission. Thermionic emission is used in a cathode-ray oscilloscope (c.r.o.) tube. 1. State why air must be removed from the tube of the c.r.o. 2. A voltage is connected across the Y-plates in the c.r.o. State and explain the effect on the trace on the screen.
5054_w13_qp_22
THEORY
2013
Paper 2, Variant 2
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319