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Current/Voltage characteristics.

Filament Lamp:
For a filament lamp, the graph curves because as the filament heats up, its resistance heats
up too. As voltage goes up, current decreases.

For a resistor current is directly proportional to the voltage.

Since current is only allowed in one direction through a…

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Resistance decreases as temperature increases.

LDR ­ Light Dependent Resistor
Resistance decreases as light intensity increases.

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Power is defined as the rate of transfer of energy. It is measured in watts (W), where 1W
= 1 joule per second i.e. P = E / t.
In electrical circuits: P = VI
This is because

1) Potential difference (V) is defined as the energy transferred per…

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Electrical energy

Sometimes you may need to find the total energy transferred, for this power must be
multiplied by time
E = Pt so E = V*I*t (time is always in seconds)

If a question asks for energy without giving power, this is the equation which should be used.


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