Download Name - edl.io

Name ____________________________
Physics Chapter 35: Series and Parallel Circuits
1. In the typical household circuit above, calculate the total resistance imposed on the circuit if all
three of them are turned on at the same time? (Look back at your notes for the common voltage
in the U.S.)
V = IR, R = V/I
R = 120 V / 20A = 6 ohms
a. What happens to the current when more appliances are added to the circuit?
The current increases, since as you add more resistors in parallel,
the resistance decreases. According to Ohm’s Law, as resistance
decreases, current increases (inverse proportion)
b. What happens to the toaster and the lamp if the heater shuts off?
Nothing. The series is in parallel, so if they shut off, it doesn’t affect the
rest of the circuit.
c. Explain why household circuits are set up in parallel.
If they were in series, if one appliance goes out, the rest will too. Which,
like, sucks.
d. What is the danger of adding too many appliances to this circuit? What might be the result?
(Hint: think about adding more resistances in parallel…)
As you add more resistors, current goes up. The current may be so much
that it trips the circuit breaker!
e. How are houses protected from the above scenario? (Hint: look at the schematic)
Circuit breakers or fuses. They will break if the current is too much.
2. What is the equivalent resistance and voltage in this circuit?
Total R = 225 Ohms
Total voltage = 270 Volts
1
0
0
.0
5
0
.0
7
5
.0
1
.2
0A
A
3. Determine the equivalent resistance and the current through the entire circuit.
4. Determine the equivalent resistance and the current through the entire circuit.
R
2
R
1
25
12.0 V
75
R
3
R
4
35
5. Determine the equivalent resistance and the current through the entire circuit.
55
6. A Circuit is set up as shown. (a) What is the total resistance? (b) What is the current? (c)
What is the power dissipated by the 18.0  resistor?
18.0 
65.0 
15.0 
15.0 V
10.0 
12.0 