Electricity and Magnetism

Practice past-paper questions

Practise O/L exam questions on Electricity and Magnetism with worked solutions

1. 2023 · Paper II · 7 marks
   Three resistors of 4 Ω, 6 Ω and 12 Ω are connected in parallel to a 12 V battery. (i) Draw the circuit diagram. (ii) Calculate the total resistance of the combination. (iii) Calculate the total current drawn from the battery. (iv) State Ohm's Law.
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   (ii) 1/R_total = 1/4 + 1/6 + 1/12 = 3/12 + 2/12 + 1/12 = 6/12 → R_total = 2 Ω (iii) I = V / R = 12 / 2 = 6 A (iv) Ohm's Law: the current through a conductor is directly proportional to the potential difference across it, provided the temperature remains constant (V = IR).
   Source: NIE O/L Science 2023 Paper II Q9

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