# Electricity, work and energy revision

- Created by: Sophie
- Created on: 15-05-14 18:32

First 276 words of the document:

Work, power and elect ricity

Work (done) = force x distance

Work = energy transferred

Units

Kinetic energy = ½ x mass x speed 2 Energy- Joules (J)

Force- Newtons (N)

Gravitational potential energy = weight (or mass x g) x height Power- Watts (W)

Voltage- Volts (V)

Work/energy = power x time Current- Amperes/amps (A)

Charge- Coulombs (C)

Energy = voltage x current x time (E=VIt or E=Pt or E=VQ) Resistance- Ohms ()

Voltage = current x resistance (V=IR)

Charge = current x time (QIt)

Power = current x voltage (P=IV)

Notes about work and energy

- As energy is never lost, only transferred, all gravitational potential energy (GPE) of a falling

object becomes kinetic energy (N.B. Energy transferred = work)

- Power is the rate of doing work/transfer of energy

Electricity

-An electric current is a flow of

negatively charged ions

Symbol -Current is rate of flow of charge

Current I -Voltage is energy transferred per

coulomb of charge

Charge Q

-Voltage between 2 points is

Time t (lowercase) number of joules converted per

Voltage V coulomb of charge that flows

between them

Energy E

-Electrons carry the charge

Resistance R -Higher resistance smaller

Power P current

-N.B. In parallel (current has more

than one path way to flow), if one

component breaks, the others stay on- so these circuits are

better for domestic lighting, so if one bulb breaks, the

others won't all switch off too

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