Series and Parallel Circuits

Question 1

A battery of electromotive force 6.0 V and of negligible internal resistance is used in the circuit. The current from the battery is 30mA, the current in resistor X (first branch) is 10mA, the resistors Y and Z (second branch) are identical. What is the power dissipated in resistor Z?

Answer 1

= 60mW
1. using P = VI
2. determine current through second branch = 30 - 10 = 20mA
3. current though a identical components on the same branch is the same
4. potential difference = 6/2 = 3V
5. 3 x 20 = 60mW