CAIE IGCSE Physics 4.2.5.3 Recall/use: for electrical energy E =

Practise using E = IVt and related power-time reasoning to calculate energy transferred by resistors, lamps, heaters and batteries.

Exam points

calculate energy transferred from current, p.d. and time using E = IVt
rearrange E = IVt to find operating time for a battery or resistor
recognise IVt as energy in joules and convert minutes or hours before substitution

[Maximum number: 2]

Fig. 9.1 shows a 12 V battery connected in a circuit containing resistors A, B, C and D. Each resistor has a resistance of $6.0 \Omega$ .

Fig. 9.1

Calculate

the energy transferred from the battery to the circuit in 50 s .
energy transferred =

$\begin{aligned} (E=) \text { IVt OR } 1.2 \times 12 \times 50 \text { OR } I^{2} \text { Rt OR } 1.2^{2} \times 10 \times 50 \text { OR } V^{2} t / \text { R OR } 12^{2} \times 50 / 10 720 \mathrm{~J} \end{aligned}$
C1
A1
Total: 7

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4.2.5.3—Recall/use: for electrical energy E = question 1