1) What does Ohm’s Law state? a) Voltage equals power times resistance b) Current is proportional to voltage and inversely proportional to resistance c) Resistance equals power divided by voltage d) Voltage is always constant in a circuit 2) What is the formula for calculating current using Ohm’s Law? a) I=V×R b) I=P÷V c) I=V÷R d) I=R÷V 3) What is the formula for calculating power? a) P=V÷I b) P=I×V c) P=R÷I d) P=V+I 4) What size MCB is required for a 3.5kW immersion heater on a 230V supply? a) 13A b) 15A c) 16A d) 20A 5) What current will flow to an 8kW shower on a 230V supply? a) 23.5A b) 30.2A c) 34.8A d) 36.5A 6) What is the resistance of a motor drawing 0.23A at 230V? a) 100Ω b) 500Ω c) 1000Ω d) 1500Ω 7) In a series circuit, how does current behave? a) It splits equally between components b) It flows through each component in turn c) It flows only through the first component d) It reverses direction 8) What is the current in a 40W bulb on a 230V supply? a) 0.087A b) 0.174A c) 0.261A d) 0.435A 9) What is the resistance of a 40W bulb on a 230V supply? a) 529Ω b) 1150Ω c) 1321.8Ω d) 2643.6Ω 10) What happens to current when resistance doubles in a series circuit? a) It doubles b) It stays the same c) It halves d) It becomes zero 11) In a series circuit with two identical bulbs, what voltage is across each bulb? a) 230V b) 115V c) 60V d) 40V 12) In a parallel circuit, how is voltage distributed? a) It is divided equally b) It is halved c) It is the same across all components d) It depends on resistance 13) What is the total current in a parallel circuit with 40W, 60W, and 100W bulbs on a 230V supply? a) 0.435A b) 0.609A c) 0.869A d) 1.0A 14) What is the formula to calculate resistance? a) R=V÷I b) R=I÷V c) R=P÷I d) R=V×I 15) Why is Ohm’s Law important for plumbers? a) To calculate water pressure b) To size fuses and MCBs c) To measure pipe diameter d) To test gas flow

Electrical Calculations

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