Current, Voltage and Resistance are typical terms that are offered to describe electricity in circuits.

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Current is the lot of fee that passes with a allude in a conductor every second. The symbol for current is I and also the unit is amps (A).

Voltage (potential difference) is the work done to move a charge versus an electrical field in between two points. The symbol because that voltage is V and also the unit for voltage is volts (V)

Resistance is a measure of how piersonforcongress.complicated it is for existing to circulation through a material. The symbol for resistance is R and resistance is measure in ohms (Ω). There space several factors that effect the resistance of a conductor:

Length – If the material has a much longer length, this will an outpiersonforcongress.come in a greater number the collisions with various other ions in ~ the conductor, raising the resistance and also making it harder for the existing to flow.Cross-sectional area – With a large cross-sectional area, over there is less chance the collisions and also the resistance will decrease.Temperature – greater temperatures will result in an boosted vibration of the ions, make the possibilities of electron colliding higher and the resistance will increase.

Ohm’s Law:

Ohm’s law describes the relationship in between current, voltage and also resistance:


= the voltage (in V)

= the present (in A)

= the resistance (in Ω).

Ohmic and also non-ohmic resistors:

Ohmic conductors follow Ohm’s law and have a constant resistance. The resistance the non-ohmic conductors varies for various voltages. Irradiate bulbs are an instance of a non-ohmic conductor. The resistance of light bulb boosts as the temperature of the filament increases.

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Ohmic and also non­-ohmic conductors can be discover by plotting a graph of present vs voltage. The graph for an ohmic conductor is a straight line. The resistance can be found from the gradient that the graph. The existing vs voltage graph for a non-ohmic conductor is not a directly line.


Example 1:

What voltage will flow through a wire through a resistance of 1.5Ω to produce a present of 4A?




= 4A

= 1.5Ω


= 6V

Example 2:

What is the resistance that a wire that produces a existing of 8A when a voltage the 2V is applied?