1. THE FILAMENT LAMP Circuit Forward characteristic Reverse

2. A V + 12 volt d.c. supply _ Ammeter Filament lamp A Variable resistor
61mA
54mA
0mA
42mA
25mA A
Variable resistor
6.0V
4.5V
0.0V
1.5V
3.0V V V
Voltmeter
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3. Potential Difference (volts) Current (m A) A 0.0 25 1.5 V 42 3.0 4.5_ +
Potential
Difference (volts)
Current
(m A)
54mA
25mA
61mA
63mA
0mA
42mA A
0.0 25
1.5
4.5V
3.0V
7.5V
6.0V
0.0V
1.5V V 42
3.0
4.5 54
6.0 61
7.5 63
Turning the battery round makes the current flow the other way through
the lamp and this gives us a graph in the
bottom left quadrant of the graph paper

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5. Potential Difference (volts) Current (m A) A 0.0 -25 -1.5 V -42 -3.0_ +
Potential
Difference (volts)
Current
(m A)
-54 mA
-25 mA
-61 mA
-63 mA
0mA
-42 mA A
0.0
-25
-1.5
-4.5 V
-3.0 V
-7.5 V
-6.0 V
0.0V
-1.5 V V
-42
-3.0
-4.5
-54
Turning the battery round makes the
current flow the other way through
the lamp and this gives us a
graph in the bottom left
quadrant of the graph paper
-6.0
-61
-7.5
-63

6. Current (I) in mA Forward characteristic p.d. (V) in volts Reverse
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