Electricity: Terms

Electricity is the effect caused by the presence or movement of charged particles.

The most important terms of electricity are: Voltage, Current, Resistance, Electric Energy and Power.

Voltage

Voltage is the potential difference or “pressure” that makes electricity flow.

• It is represented by the symbol V (volt).
• V stands for voltage.

• Volts (V) are the unit representing voltage.

The voltage used in an ordinary household appliance is 120 V in the United States, 240 V in Europe, and 100 V in Japan.

Current

Current is the quantity of electricity flowing per second trough an electric line.

• It is represented by the symbol I.
• I stands for current.

• Amperes or Amps (A) are the unit representing current.

1 A     = 6,240,000,000,000,000,000 electrons/s

Resistance

Resistance is a measure indicating the difficulty of the flow of current.

• It is represented by the symbol R.
• R stands for resistance.

• Ohms (Ω) are the unit representing resistance.

Resistivity measures how much a material opposes the flow of current and can be used to determine a wire’s resistance.

Electric energy

Electric energy is the amount of work done by an electric device.

• It is represented by the symbol E.
• E stands for energy.

• Energy is often measured by power companies in kilowatt hours (kW·h).

The amount of energy is calculated by multiplying the power it drains and the time the device operates. Example: 1200 W · 2 hours = 2400 W·h = 2,4 kW·h

Power

Power is the electric energy consumed in one second when current flows.

• It is represented by the symbol P.

P stands for power. Watts are the unit representing power.

Ohm’s law

The current I is directly proportional to the voltage V and inversely proportional to the resistance R.