Science 9 Ch 8 Practice
Name___________________
1. Circuit A
2. Circuit B
3. Circuit C
1. Circuit diagram
2. Circuit diagram
3. Circuit diagram
Complete the statements.
a) If you increase the current, the:
a. voltage will __________________.
b) If you increase the voltage, the:
a. current will __________________.
c) If you increase the resistance, the:
a. current will __________________.
b. voltage will __________________.
d) If you decrease the resistance, the:
a. current will __________________.
b. voltage will ________________.
e) If you decrease the current, the:
a. voltage will __________________.
f)
If you decrease the voltage, the:
a. current will __________________.
Convert the following:
a) 17 A = _____mA
b) 1.25 A = ____mA
c) 156 mA = _____ A
d) 12.4 mA = ____A
e) 1700 Ω = ____ k Ω
f) 35 k Ω = ____ Ω
1
Give the value of each resistor indicated by the colour bands.
1st band
colour
2nd band
colour
3rd band
colour
(a)
blue
green
red
(b)
violet
black
yellow
(c)
green
blue
brown
(d)
brown
red
black
(e)
grey
violet
orange
(f)
red
brown
red
Work
Resistor Value
()
True or False?
Read the statements given below. If the statement is true, write “T” on the line in front of the statement. If it is false,
write “F” and rewrite the statement to make it true.
____1. An electric circuit is a complete pathway
through which electrons can flow.
____6. Circuit diagrams use circuit symbols to illustrate
actual electrical circuits.
____2. An electric load transforms light energy into
electrical energy.
____7. Current electricity is charge that remains
stationary on an insulator.
____3. Light bulbs, heaters, and batteries are all
examples of electric loads.
____8. Electric current is the amount of charge passing
a point in a conducting wire each second.
____4. The wire through which electric current flows is
a conductor.
____9. Electric current is measured in volts.
____5. A switch is the source of electric potential
energy in a circuit.
____10. An ammeter is used to measure the current in
a circuit.
2
Ohm’s Law Calculations. Show Your Work!
1. What is the resistance of a toaster if a
current of 12.5 A flows through it when it is
connected
to 120 V?
5. A flashlight bulb has a resistance
of 4.0 What current passes through the
bulb if it is connected to 3.0 V?
2. A light bulb has a resistance of 90 What
current flows through the bulb when it is
connected to 120 V?
6. What potential difference is necessary to
produce a current of 0.60 A in a load that
has a resistance of 25 
3. A current of 0.50 A flows through a light bulb
that has a resistance of 18 What is the
voltage across this light bulb?
7. The current through a load in a circuit is 2.5
A. If the potential difference across the load
is 75 V, what is the resistance of the load?
4. Only 2.5 × 103 A of current pass
through a portable CD player. If the CD
player is operated by a 9.0 V battery, what is
the resistance within the circuit?
8. An automobile headlight has an average
resistance of 24 . Car batteries provide a
potential difference of 12 V. What amount of
current passes through the headlight?
3
9. In a portable radio, 0.50 A of
current are flowing through a conductor that
provides 18  of resistance. What potential
difference is provided by the battery?
10. A clothes dryer uses a 220 V power
source. The coils of the heater provide
an average resistance of 12 . What
amount of current is flowing through the
heating coils?
4
Ohm’s Law Equations
1. A current through a resistor in a circuit is 1.5 A. If the
potential difference across the resistor is 6 V, what is
the resistance of the resistor?
𝑅 =
5. An electric iron plugged into a wall socket has a
resistance of 20 Ω. If the current in the iron is 6 A, what
is the voltage provided by the wall socket?
𝑉
𝐼
2. A toaster is plugged into a 120 V outlet. What is the
resistance of the toaster if the current in the toaster is
10 A?
6. A 1.2 A current flows through a 250 ohm resistor.
Calculate the voltage across this resistor.
3. A light bulb with a resistance of 30 Ω is connected to
a battery. If the current in the light bulb is 0.2 A, what is
the voltage of the battery?
7. A 120 Ω resistor is connected to a 12 V battery.
Calculate the current through the resistor.
4. What is the current in a flashlight bulb with a
resistance of 24 Ω if the voltage provided by the
flashlight battery is 3 V?
8. An unknown resistor transforms 2.0 mA of current
when connected to a 9.0 V battery. Calculate the value
of this resistor.
5