Essential Electricity
Homework Exercise 1
For each of the following electrical symbols, copy the symbol
into you jotter and label it using the words below.
Word bank
resistor, voltmeter, battery, ammeter, bulb
V
A
1. State the energy change in each of the following:
(a) Lamp
(b) Battery
(c) Electric motor
(d) Electric buzzer
3. Draw (neatly) a series circuit with a battery, a switch and
a lamp.
Essential Electricity
Homework Exercise 2
1. What is used to measure electrical current in a circuit?
2. Describe what is meant by electrical current.
3. What is electrical Current is measured in?
4. For each of the circuits copy the diagram and fill in any
missing Current and Voltage values;
(a)
12V
5A
3V
(b)
3A
1A
3V
Essential Electricity
Homework Exercise 3
1. What is used to measure Voltage in a circuit?
2. Name the unit Voltage is measured in?
3. For each of the circuits copy the diagram and fill in any
missing Voltage values;
(a)
6V
3A
2V
(b)
4A
2A
3V
Essential Electricity
Homework Exercise 4
1. Describe the energy change in a resistor.
2. Name the unit Resistance is measured in?
3. What meter is used to measure resistance?
4. A resistor has a voltage of 6V across it and a current of
2A through it. Calculate the value of the resistor.
5. If the resistance in a circuit increases what happens to
the current in the circuit?
6. Variable resistors can be used for speed control of a
remote control car. Can you name 2 other uses?
Essential Electricity
Homework Exercise 5
1. A variable resistor is used in the speed controller of a toy
electric train. The variable resistor controls the current flowing
to a small electric motor in the train shown in figure 1
Copy the diagram and complete it by
adding a variable resistor.
2. At one particular speed the voltage across the variable
resistor is 6.0 volts and the current flowing through it is 0.3
amperes.
a. Calculate the resistance of the variable resistor
b. What is the current flowing through in the motor?
The resistance of the variable resistor in the speed control is
now decreased
c. What will happen to the current following in the motor?
d. What effect will this have on the speed of the toy
train?
e. Give two other uses of a variable resistor
Essential Electricity
Homework Exercise 6
1. A resistor has a voltage across it of 12 volts and a
current through it of 2.5 amperes. Calculate the
resistance of the resistor.
2. A voltage of 6 volts is across a resistor where the current
is 0.5 amperes.
What is the value of the resistor?
3. Calculate the resistance of a component when a voltage
of 24 V causes a current of 0.1 amperes.
4. If a current of 2 amperes exists through a lamp when it
has 12 volts across it, what is the resistance of the
lamp?
5. A torch bulb is marked "6 V, 0.25 A”. Calculate the
resistance of the bulb. Solution
Essential Electricity
Extra Revision Questions 1
1. Draw the circuit diagram symbols for a battery, a bulb and a
resistor?
2. Sort the following materials into conductors or insulators.
Show your answers in a table.
Gold, rubber, plastic, copper, carbon, wood, air, silver,
aluminium, paper, lead, wool.
3. What would you use to measure resistance?
4. For each of the circuits copy the diagram and fill in any
missing Current and Voltage values;
(b)
24V
8A
9V
(b)
6A
3A
12V
Essential Electricity
Extra Revision Questions 2
1. Which has a higher resistance rubber or copper?
2. Which has a higher resistance a thick wire or a thin wire.
3. A resistor has a voltage of 9V across it and a current of
3A through it. Calculate the value of the resistor.
4. State three advantages of a ring circuit.
5. Can you design a circuit that would allow you to test for
faults in a circuit? Draw a neat diagram of the circuit.
Extra Revision Questions 3 Essential
Electricity
1. Draw and label the symbols for a battery, a lamp, a switch
a resistor and a variable resistor.
2. How do you tell the difference between a parallel circuit
and a series circuit?
3. What happens to the brightness of a bulb in a series
circuit if you increase the resistance?
4. On this circuit, draw an ammeter to measure the current
and a voltmeter to measure the voltage across the bulb.
Make sure you show how ammeters and voltmeters are
connected into a circuit.
5. A small motor operates at 12 volts and carries a current of
amps. What is the resistance of the motor?
6. What is an ohm-meter used to measure?