Question
(a) A student investigates the electrical resistance of some components.
Fig. 10.1 shows an incomplete diagram of the circuit used by the student.
(i) State the term used for component Y.
(ii) The student uses the circuit to measure the resistance of component Y.
Complete the diagram in Fig. 10.1 by adding electrical symbols to show an ammeter and a voltmeter correctly connected to determine the resistance of component Y.
(b) Fig. 10.2 shows two resistors A and B.
(i) Resistor A and resistor B are connected in series.
State the value of their combined resistance.
…………………….. Ω
(ii) Resistor A and resistor B are connected in parallel.
(iii) Compare the combined resistance when in parallel with the resistance of resistor A alone.
Answer/Explanation
Answer:
(a) (i) thermistor
(ii) correct symbol for ammeter drawn
correct symbol for voltmeter drawn
both meters correctly positioned in circuit
(b) (i) 12 (Ω)
(ii) smaller (than A)
Question
A student makes the circuit shown in Fig. 10.1 using a 12 V battery.
(a) Complete the sentences about the circuit. Use words from the box.
(i) Components X and Y are connected in
(ii) The component Y is a
(b) Fig. 10.2 shows how the resistance of Y varies with temperature.
i. Describe how the resistance of Y varies with temperature.
ii. The temperature of Y is 10 °C. The resistance of X is 20 Ω.
Calculate the combined resistance of Y and X.
resistance =
iii. Calculate the current in the circuit.
current =
Answer/Explanation
Answer:
(a)(i) series
(a)(ii) thermistor
(b)(i) resistance decreases as temp increases
at decreasing rate OR not proportional OR not linear
(b)(ii) resistance of Y = 80 Ω
\(R_t = R_1 + R_2\) in any form
100( Ω)
(b)(iii) V = I R in any form
12 ÷ 100 OR 12 ÷ candidates (b)(ii)
0.12 (A) OR ECF from (b)(ii)