Unit 21: Electric Circuits, Ohm’s Law, & Power

Practice Problems

Note: problem difficulty is ranked using a star system.

  • (*) One-star problems are fundamental to the unit, and can be done relatively quickly. Use these problems to introduce yourself to the material.

  • (**) Two-star problems are more difficult, and require an understanding of one or two key concepts. Use these problems to test your understanding of the material.

  • (***) Three-star problems are the most difficult, and require some creative thinking in addition to a deep familiarity with multiple key concepts. Use these problems to challenge yourself; if you can complete one of these, you’re on your way to mastering the material.

*Q21.1) A 120 V battery powers a circuit with a total resistance of 240 Ω.

a) How much current flows out of the battery?

b) How much power is dissipated by the circuit?

c) How much energy is dissipated by the circuit in 10 minutes?

**Q21.2) Find the total current flowing through the following circuit:

**Q21.3) Find the current flowing through each of the resistors in the following circuit:

***Q21.4) Find the following properties of the circuit shown below:

a) The current flowing through each resistor.

b) The voltage drop across each resistor.

c) The power dissipated by each resistor.

Note: you may want to solve for these properties in a different order to what’s shown above.