Electric Current and Ohm’s Law

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Electric Current• A continuous flow of electric charge.• Measured in amps (A) = 1 coulomb per

second• Direct current (DC) when charge flows in

one direction• Alternating current (AC) is a flow of

electric charge that regularly reverses direction.

• EX – home plugs and lights

Electrical Conductors and Insulators

• Conductors are materials through which charge can easily flow– Metals and water

• Insulators are materials through which a charge cannot flow easily.– Wood, plastic, rubber and air

Resistance

• Opposition to the flow of charges in a material

• Measured in ohm.

• A material’s thickness, length, and temperature affect its resistance.

• A thinner, longer and hotter wire increase resistance.

• Superconductor has almost 0 resistance

Voltage• In order for a charge to flow in a wire,

the wire must be connected in a complete loop that includes an energy source.

• Potential difference - difference in potential energy between 2 places in an electric field

• Measured in volts – joules per coulomb

• Batteries convert chemical energy into electrical energy.

Ohm’s Law• Voltage (V), in a circuit equals the

product of the current(I) and the resistance ( R).

• V = I x R or I = V/R

• Increasing voltage increases current. Keeping same voltage and increasing the resistance decreases the current