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Slide 2

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What is a potential
·
divider?
A potential divider is basically two
3
resistors.
V
· The current flows through the two 3
resistors which will split the potential
· From the equations show right, you can
see that the total potential difference V1 = IR1
across the two resistors have been divided V2 = IR2
up by a ratio of their two resistances.
· By choosing values of R1 and R2 that are
V1 = R1
appropriate, any voltage between zero V2 = R2
and V can be obtained across either of the
two resistors.…read more

Slide 3

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Worked example
What is the potential difference across each resistor?
V1 = 36 ohms
V2 = 12 ohms
First work out the total current
V = IR so V/R = I
36 V1 Total V = 12V
Total R = 36 + 12 = 48 ohms
12V
12 / 48 = 0.25A
12 V2
Now multiply each resistance value by current to get
the potential difference across each
V = IR
V1 = 0.25 x 36 = 9V
V2 = 0.25 x 12 = 3V…read more

Slide 4

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The potentiometer
· Where a continuously varied potential
difference is needed, the fixed resistors are
replaced with a potentiometer.
· This device has a long length of resistance wire
or carbon track, with a slider (wiper) that can be
moved to vary the potential difference.
· This allows R1 and R2 to be varied which the
overall R remains the same.
· It can be continuously varied from 0 to a…read more

Slide 5

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Which is the best
circuit?
A
A…read more

Slide 6

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This one...
Why?
Using this circuit you can alter the
resistor to achieve a voltage of 0V
A
to a maximum voltage, whereas
with the other circuit you cannot
reach 0V. Therefore the range of
voltages reached with this circuit is
much larger than that of the other
circuit. This is better for working out
voltages and currents by changing
the resistance, as you can start
from the lowest voltage possible.…read more

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