PH202-OX
Summer 2014
Worksheet June 19
Resistance
What is resistance?
How is resistance related to current and voltage? What is the unit of measurement for resistance?
Resistors wired in series and in parallel
When resistors are wired in series, what do you know about the current through each resistor and
the potential difference across each resistor?
How do you find the equivalent resistance of resistors wired in series?
When resistors are wired in parallel, what do you know about the current through each resistor and
the potential difference across each resistor?
How do you find the equivalent resistance of resistors wired in parallel?
Kirchhoff’s rules
What is Kirchhoff’s loop rule? Can you express the rule as a mathematical statement?
What is Kirchhoff’s junction rule? Can you express the rule as a mathematical statement?
PH202-OX
Summer 2014
Describe the four steps necessary to solve a circuit problem using Kirchhoff’s rules.
How do you decide which direction the current flows in a branch of a circuit?
When applying the loop rule, how do you decide whether a battery has a positive or negative
potential difference? How do you decide for a resistor?
Problems
1. Three resistors have resistances of 4.3 Ω, 1.7 Ω, and 2.2 Ω. What is the equivalent resistance of
the resistors a) when they are wired in series, and b) when they are wired in parallel? If a
potential difference of 5 V is applied to the resistors, what is the current and voltage across
each resistor c) when they are wired in series, and d) when they are wired in parallel?
PH202-OX
Summer 2014
2. In the circuit shown to the right, the resistors have resistances
RA = 4.0 Ω, RB = 1.0 Ω, RC = 2.0 Ω, and RD = 3.0 Ω. Find a)
the equivalent resistance of the four resistors and b) the current
across resistor C if the battery provides a potential difference of
8.0 V.
3. Find the current direction in each branch of the
circuit to the right and the magnitude of the
current through the 9.0 Ω resistor.
PH202-OX
Summer 2014