Electric Circuits review worksheet KEY
1. B
Adding resistors in series increases the total resistance of the
circuit. By Ohm’s Law the current should DECREASE.
2. A
Your house circuits are parallel; adding resistors decreases the
total resistance of the circuit. By Ohm’s Law the current should
INCREASE.
3. series
(Only one path for charge flow.)
4. parallel
(Multiple paths for current.)
5. B
Removing a resistor causes the total resistance to increase
(less paths for charge flow) which, by Ohm’s Law, will cause the
current to DECREASE.
6. An open circuit has a break in the conductive path from high
to low potential, prohibiting the charge flow.
A closed circuit is a complete conductive path from high to
low potential; a current exists.
7. Potential Difference, or Voltage (V) – the source of
electrical energy
Current (I) – the actual flow of charge carriers from high V to
low V
Resistance (R) – transforms electrical energy to other forms;
also limits the amount of current in the circuit.
8.
a)
b)
9.
10.
11. a)
b)
c)
17. Wires have resistance; therefore, large currents in them produce significant amounts of heat
(P = I²R) that can cause fires or damage to electronic components.
18. An overload is the situation in which too many resistors have been placed in parallel. This
results in a total resistance that is very small and, by Ohm’s Law, a large current in the main
body of the circuit.
A short circuit results when wires connect where they shouldn’t, causing the current to
bypass the resistors. This leads to a circuit with very little resistance and, thus, a large
current.
19. Fuses are single-use components containing a wire that melts when the current through
them reaches a certain level.
Circuit breakers are reusable switches that open when the current through them reaches a
certain level.
20. These components must be placed in the main body of the circuit rather than a branch in
order that it receives the total current running through the circuit.
In addition, they should be placed between the high potential side of the voltage source and
the resistors (the ‘hot’ side). This insures that if the circuit is opened the resistors will be
grounded, preventing the possible electrocution of anyone coming in contact with the
resistors.