Parallel Circuit Analysis
1) Three 15 Ω resistors are connected in parallel and placed across a 30 V potential difference.
i) What is the equivalent resistance of the parallel circuit? [5.0 Ω]
ii) What is the current through the entire circuit? [6.0 A]
iii) What is the current through each branch of the parallel circuits? [2.0 A]
2) A 12.0 Ω resistor and a 15.0 Ω resistor are connected in parallel and placed across the terminals of a 15.0 V
battery.
i) What is the equivalent resistance of the parallel circuit? [6.67 Ω]
ii) What is the current through the entire circuit? [2.25 A]
iii) What is the current through each branch of the parallel circuit? [1.25 A, 1.00 A]
3) Suppose the 12.0 Ω resistor in the previous question is replaced by a 10.0 Ω resistor.
i) Does the equivalent resistance become smaller, larger, or remain the same? [smaller]
ii) Does the amount of current through the entire circuit change? In what way? [becomes larger]
iii) Does the amount of current through the 15.0 Ω resistor change? In which way? [no]
4) A 120.0 Ω resistor, a 60.0 Ω resistor, and a 40.0 Ω resistor are connected in parallel and placed across a
potential difference of 12.0 V.
i) What is the equivalent resistance of the parallel circuit? [20.0 Ω]
ii) What is the current through the entire circuit? [0.600 A]
iii) What is the current through each of the branches of the parallel circuit? [0.100 A, 0.200 A, 0.300 A]
5) Three resistors of 60.0 Ω, 30.0 Ω, and 20.0 Ω are connected in parallel across a 90.0 V difference in potential.
i) Find the equivalent resistance of the circuit. [10.0 Ω]
ii) Find the current in the entire circuit. [9.00 A]
iii) Find the current through each branch of the circuit. [1.50 A, 3.00 A, 4.50 A]
6) An engineer needs a 10 Ω resistor and a 15 Ω resistor, but there are only 30 Ω resistors in stock. Must new
resistors be purchases? Explain. [No]
7) Three identical lamps are connected in parallel to each other and then connected to a 6.0 V battery. What is
the voltage drop across each lamp? [6.0 V]
8) For the following circuit, find the current going through each resistor.
[24 A, 12 A, 8 A]