alleryStart learning →A device draws 3 A at 24 V. What electric power does it use?
- 72 W
- 27 W
- 8 W
- 720 W
Show answer and solution
Correct answer: A. 72 W
P = VI = 24×3 = 72 W.
ICSE Class 10 Electricity: Ohm's law, electrical power and energy, household circuits — practice questions — page 2
Explore 50 free Electricity: Ohm's law, electrical power and energy, household circuits questions in ICSE Class 10 Physics. Open each question or exercise to read its content, reference answers and available explanation.
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Showing questions 31–50 of 50.
A device draws 3 A at 24 V. What electric power does it use?Read the answer and worked solution →How many megajoules are equal to one kilowatt-hour?Read the answer and worked solution →A 4 Ω resistor carries 3 A. Find its power using P = I²R.Read the answer and worked solution →In a circuit, what does an electric heater do with consumed power?Read the answer and worked solution →With material and area fixed, doubling wire length makes R…Read the answer and worked solution →For unchanged material and length, how does twice the area affect R?Read the answer and worked solution →Two 5 Ω resistors are connected in series to a 2 A current. What voltage is across the pair?Read the answer and worked solution →A 6 Ω and a 3 Ω resistor are each connected across 12 V in parallel. What total current flows?Read the answer and worked solution →For two parallel resistors, equivalent resistance is…Read the answer and worked solution →What voltage is across a 10 Ω resistor carrying 3 A?Read the answer and worked solution →A 60 W device operates at 12 V. What current does it draw?Read the answer and worked solution →A 2 Ω and a 4 Ω resistor are in series on 12 V. What voltage is across the 4 Ω resistor?Read the answer and worked solution →If one parallel lamp fails, what happens to another?Read the answer and worked solution →A 12 Ω and 6 Ω pair in parallel is placed in series with 8 Ω. Find the total resistance.Read the answer and worked solution →A 2 Ω, 4 Ω and 6 Ω series chain is across 24 V. What voltage drops across the 6 Ω resistor?Read the answer and worked solution →Three 6 Ω branches are in parallel across 12 V. What total current leaves the supply?Read the answer and worked solution →A resistive lamp uses 500 W at 10 A. What is its resistance?Read the answer and worked solution →A 12 V source drives 3 A through a resistor. What is the resistance?Read the answer and worked solution →Why can a short circuit cause a fire?Read the answer and worked solution →What happens if a live wire touches an earthed case?Read the answer and worked solution →
Worked practice questions
How many megajoules are equal to one kilowatt-hour?
- 3.6 MJ
- 36 MJ
- 0.36 MJ
- 360 MJ
Show answer and solution
Correct answer: A. 3.6 MJ
One kilowatt-hour equals 3.6 megajoules.
A 4 Ω resistor carries 3 A. Find its power using P = I²R.
- 48 W
- 12 W
- 36 W
- 7 W
Show answer and solution
Correct answer: C. 36 W
P = 3²×4 = 36 W.
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