Ohm's law is V = IR and resistance is measured in ohms, so this Year 12 sheet starts from the two quantities that define a circuit. The key records an 8 Ω answer, a 2 Ω result, and P = VI for electric power.
Key Takeaways
Ohm's law is V = IR (Q1).
The SI unit of resistance is the ohm (Q2).
The key records answers of 8 Ω and 2 Ω.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.Ohm's law is correctly expressed as...
(a) V = IR(b) I = VR(c) R = IV(d) V = I/R
2.The SI unit of resistance is the...
(a) ampere(b) volt(c) ohm(d) watt
3.Two 4 Ω resistors connected in series have a total resistance of...
(a) 2 Ω(b) 4 Ω(c) 8 Ω(d) 16 Ω
4.Two 4 Ω resistors connected in parallel have a total resistance of...
(a) 8 Ω(b) 2 Ω(c) 4 Ω(d) 16 Ω
5.The electrical power dissipated in a resistor can be found using...
(a) P = VI(b) P = V/I(c) P = I/R(d) P = R/I
6.The e.m.f. of a battery is...
(a) the energy supplied per unit charge by the battery(b) the current it delivers(c) the potential difference across its terminals(d) the resistance of its internal circuit
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.State Ohm's law.
8.Define the resistance of a component.
9.Distinguish between e.m.f. and potential difference.
10.State Kirchhoff's first law.
11.State Kirchhoff's second law.
12.Define resistivity and give its SI unit.
13.What happens to the total resistance of a parallel combination when more resistors are added?
14.A voltmeter is placed in parallel with a resistor. Why must a voltmeter have a very high resistance?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A 12 V battery is connected across a 4 Ω resistor. Using Ohm's law, calculate the current.
16.Resistors of 6 Ω and 3 Ω are connected in parallel across a 12 V supply. Calculate the total resistance and the total current drawn.
17.A current of 2 A flows through a 10 Ω resistor. Using P = I²R, calculate the power dissipated.
18.A heater rated at 2 kW operates on a 240 V supply. Using P = VI, calculate the current, and using R = V/I calculate the resistance of the heater.
19.A copper wire of length 2 m and cross-sectional area 1×10⁻⁶ m² has resistivity 1.7×10⁻⁸ Ω m. Using R = ρL/A, calculate its resistance.
20.A battery of e.m.f. 12 V and internal resistance 1 Ω is connected to a 5 Ω resistor. Calculate the current using I = E/(R + r) and the terminal potential difference V = E - Ir.
Answer Key
1. a) V = IR
2. c) ohm
3. c) 8 Ω
4. b) 2 Ω
5. a) P = VI
6. a) the energy supplied per unit charge by the battery
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What is Ohm's law?
V = IR, option (a) in this worksheet (Q1).
What is the unit of resistance?
The ohm, option (c) in this worksheet (Q2).
What is the formula for electric power?
P = VI, from the answer key on this page.
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