Teacher's notes and answers to questions in the book - Hodder Plus ...

WJEC GCSE Additional Science Teacher’s Notes
14
Simple electrical circuits
_ Simple electrical circuits (pages 153–61)__________
PRACTICAL Measuring currents in series and parallel
circuits (page 154)
Students set up series and parallel circuits to determine that current is the same all the way
around a series circuit, and that when current splits at a junction in a parallel circuit, the sum of
the currents going into the junction equals the sum of the current coming out of the junction.
This is best shown with bulbs of different powers.
Questions
1. Study the following circuits. Use your knowledge of the behaviour of current in series and parallel
circuits to calculate the current at each of the marked points on the circuit diagrams (a to j in Figure
14.6).
a 0.4 A d 0.2 A g 0.3 A j 1.2 A
b 0.4 A e 0.6 A h 1.2 A
c 0.4 A f 1.5 A i 0.3 A
2. In a domestic house, all the electrical sockets, and all the domestic appliances such as an electric oven,
are connected in parallel to the main circuit board. In one such house during the early evening, the
lights are using 2.5 A, a television 0.5 A, an electric oven 13 A and a kettle 10 A. What is the total
current drawn from the main circuit board
Total current = 2.5 + 0.5 + 13 + 10 = 26 A
3. Draw circuits showing the following:
a Two bulbs and a switch in series with a b A solar cell connected in parallel with two filament
6 V power supply unit. lamps, each one with its own switch in series.
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