Alternating current and direct current

3 marks · Easy

A torch bulb is connected to a battery that supplies a voltage of 4.5 V and a current of 0.2 A.

(a)

Calculate the power of the bulb.

[1 mark]

(b)

The bulb is turned on for 10 minutes. Calculate the total energy transferred.

[2 marks]

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(a) 0.9 W

(b) 540 J

Show mark scheme and worked solution

Marking points

M1 (a) · 1 mark · Uses P = I × V with correct substitution (0.2 × 4.5)

M1 (b) · 1 mark · Converts 10 minutes to seconds or uses correct time in calculation.

A1 (b) · 1 mark · Accurate calculation of energy transferred (540 J) (follow-through)

Worked solution

a) Using P = I × V:

b) First, convert 10 minutes to seconds:

Then use E = I × V × t: