This document discusses series circuits and the rules that govern their behavior. It explains that in a series circuit, the current is the same through all components and the voltage is shared across the components. It also notes that the total resistance of components in series is calculated by adding the individual resistances together. Several examples are provided to demonstrate how changing components in a series circuit impacts the current, voltage, and resistance. Key equations for calculating current, voltage and resistance in series circuits are also shown.

1. Type your answers in the black boxes and check them with the correct
answers on the last slide

2. Rules
Current is the same through all the components
Voltage is shared out across the components
The resistance of components adds together
Potential difference = current x resistance
volts = amps x ohms

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3A
3A
3A
3A
3A
THE CURRENT IN A SERIES
CIRCUIT IS THE SAME AT
EVERY POINT.

5. What happens if one lamp is unscrewed?
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No current flows if there is a gap in the
circuit

6. What happens if one cell is turned around?
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Reversing the cell reverses the pushing effect
(cells provide a pd to push the charge)

7. What happens if another cell is added
the same way as the others?
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Increasing the pd in the same direction
increases the pushing effect on the charges

8. What happens if another cell is added
the other way to the others?
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Adding pd in the opposite direction makes
the pushing effect on the charges less

9. What happens if another bulb is added?
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Adding a bulb adds resistance to the flow
of charge

10. What happens if both cells are turned around?
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The pd pushes the current the other way but
the brightness of the bulbs remains the same.
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11. Equations
V = I x R I = V/R R = V/I
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3A
6V battery
2 Ohm 4 Ohm
Adding resistors in series is
dead easy- the total resistance
is now 6 Ohm
Divide the voltage by the total resistance
and type your answer with units in the box
Question 1 Using the equation for current (I) we
can work out that 3Amps of
current will be flowing

12. Equations
V = I x R I = V/R R = V/I
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1A
12V battery
R R
Total Resistance =
Value for R =
Work out the total resistance of the circuit
and a value for R
Question 2

13. Equations
V = I x R I = V/R R = V/I
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A
12V
1 Ohm 3 Ohm
V V
Notice that the circuit is NOT affected by the
meters and the resistors are still in series
I = 12/4 = 3A
3A
V V
pd across
the 1 Ohm
resistor
Question 3
pd across
the 3 Ohm
resistor

14. Rules you should remember and be able
to use:-
Current is the same through all the components
Voltage is shared out across the components
The resistance of components adds together
Potential difference = current x resistance
volts = amps x ohms

15. answers
Question 1 1Amp
Question 2 Total Resistance = 12/1 = 12 Ohms
If the resistors are both the same
then R = 6 Ohms
Question 3 PD across 1 Ohm resistor = 3 Volts
PD across 3 Ohm = 9 Volts