EE4: Practical Electricity: Voltage Current & Resistance
1 (a) 3 identical lamps are connected as shown in circuit 1. A 12.0 volt battery supplies a
current of 0.2 amperes.
(i)
(ii)
State the current in lamp 2
Calculate the voltage across lamp 2
(1)
(2)
(b) The lamps are now connected as shown in circuit 2. The 12.0 volt battery supplies a
current of 0.40 amperes to this circuit.
(i)
Complete the table to show the current in each lamp and the voltage across
each lamp.
Lamp 1
Lamp 2
Lamp 3
Voltage(volts)
8.0
Current(amperes)
0.4
(2)
2.
A circuit is set up as shown
The current from the supply is 6A. The current in the resistor is 1.5 A.
What is the current in, and potential difference across resistor R2 .
3.
(2)
A circuit is set up as shown
Which switch or switches must be closed to light lamp L1 only?
(2)
4. The circuit shown is used to control the brightness of two identical lamps. The variable
resistor is adjusted until the lamps operate at their correct voltage of 3.0V
(a)
(b)
(c)
(d)
(e)
When the lamps operate at the correct voltage, the reading on the ammeter is
1.2A. Calculate the current in one lamp.
(3)
Calculate the resistance of one lamp.
(3)
Calculate the combined resistance of the two lamps in this circuit.
(3)
When the lamps operate at their correct voltage the resistance of the variable
resistor is 7.5Ω. Calculate the total resistance in the circuit.
(3)
One of the lamps is removed. Explain what happens to the reading on the
ammeter. You must justify your answer
(2)
5. A student has 4 resistors labelled A, B, C and D.
The student sets up Circuit 1 to identify the value of
each resistor.
Each resistor is placed in the circuit in turn and the
following results are obtained.
Resistor
A
B
C
D
(a)
Voltage across
resistor (v)
6.0
6.0
6.0
6.0
Current (A)
0.017
0.027
0.050
0.033
(i) Show by calculation, which of the resistors has a value of 120Ω.
(3)
(ii) The student the sets up Circuit 2 to measure the
resistance of each resistor.
State one advantage of using circuit 2 to measure the resistance
compared to using circuit 1. (1)
(b)
6.
The resistances of the other three resistors are 180Ω,
220Ω and 360Ω. The student connects all four
resistors in series. Calculate the total resistance.
(3)
A circuit is set up as shown.
What is the reading on the ammeter and the voltmeter
(7)
7. A 9v battery supplies a current of 2A in a lamp. Use your knowledge of voltage and
current to determine how much energy lamp receives each second?
(3)
(40 marks)