Electrical Power and Energy Transfers in Appliances

Electrical Power

Power measures the rate at which energy is transferred by a device, often expressed in terms of energy per second. This means that a more powerful device will transfer more energy over a period of time.

We can calculate the power transferred in a device or appliance using the potential difference and current. The equation is:

However, if we don’t know the potential difference value, we can also calculate power using the current and resistance of the device or appliance.

  • P = Power in watts (W)
  • V = Potential difference in volts (V)
  • I = Current in amperes (A)
  • R = Resistance in ohms (Ω)

Energy Transfers in Appliances

Every electrical appliance transfers energy from one store to another. Whenever charge flows in a circuit, electrical work is done.

How much energy is transferred by an electrical appliance depends on:

  • The time the appliance is on for
  • The power of the appliance

We can calculate the energy transferred by an appliance using the equation:

  • E = Energy transferred in joules (J)
  • P = Power in watts (W)
  • t = Time in seconds (s)

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