9702/02/SP/22 · question 2 of 2 in this topic
Three resistors of resistances R₁, R₂ and R₃ are connected as shown in Fig. 6.1.
The currents in the resistors are I₁, I₂ and I₃. The total current in the combination of resistors is I and the potential difference across the combination is V.
Show that the total resistance R of the combination is given by the equation
1/R = 1/R₁ + 1/R₂ + 1/R₃.
Show The result is given, so every step of the reasoning is what earns the marks.
Your answer
Suggested time: 3 min
A battery of electromotive force (e.m.f.) 6.0 V and internal resistance r is connected to an external resistor of resistance 12 Ω and a thermistor X, as shown in Fig. 6.2.
By considering energy, explain why the potential difference across the terminals of the battery is less than the e.m.f.
Your answer
Suggested time: 2 min
A battery of electromotive force (e.m.f.) 6.0 V and internal resistance r is connected to an external resistor of resistance 12 Ω in parallel with a thermistor X.
A charge of 2.5 kC passes through the battery.
Calculate:
• the total energy transferred by the battery
• the number of electrons that pass through the battery.
Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.
Your answer
Suggested time: 5 min
A battery of e.m.f. 6.0 V and internal resistance r is connected to an external resistor of resistance 12 Ω and a thermistor X in parallel.
The combined resistance of the external resistor and thermistor X connected in parallel is 4.8 Ω.
Calculate the resistance of X.
Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.
Your answer
Suggested time: 2 min
A 12 Ω resistor is connected in parallel with a thermistor X; the combined resistance is 4.8 Ω, so the resistance of X can be found (as in (b)(iii)).
Use your answer in (b)(iii) to determine the ratio
(power dissipated in thermistor X)/(power dissipated in 12 Ω resistor).
Using You must use the thing it names. An answer that reaches the right value another way may not score.
Your answer
Suggested time: 3 min
9702/02/SP/22Cambridge International AS & A Level Physics 9702 · Specimen 2022 · Paper 2 · sit the whole paper