Electrical power and energy – basic principles
How it works
Electrical power (P) indicates how much electrical energy is converted per unit of time. It is measured in watts (W). In simple circuits, electrical power is calculated using P = U × I, where U is the voltage (in volts) and I is the current (in amperes). If the power remains constant over a certain time, the following applies to electrical energy: E = P × t. Energy is given in joules (J) or kilowatt-hours (kWh). For conversions, the following applies: 1 kWh = 3 600 000 J. The energy consumed depends on how large the power of a device is and how long it is operated.
Electrical power is calculated using P = U × I. If the power is constant, the electrical energy is obtained from E = P × t.
An example
A toaster operates with a voltage of 230 V and a current of 4 A. How large is its electrical power?
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50 Exercises
To the learning unit →Own explanation and own practice exercises by AmyMath. Subject reference framework: Physics. The topic assignment may vary by federal state.