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Resistance Heating

The heating effect of a current is due to the resistance of the circuit.The power P is the rate of energy transfer and is due to the current and the potential difference.

P = I V

This could also be written as

P = I2R

or

P= V2/R

since V = IRCharge carriers repeatedly collide with positive ions in the conducting material and transfer their kinetic energy to the positive metal ions as a result.The positive ions vibrate more and the internal energy of the metal increases.The potential difference then accelerates the charge carriers until they collide with another ion.If the component is at a constant temperature the energy transfer takes place at a constant rate.The energy transfer does not depend on the direction of the current.

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Specification: AQA Physics (7407), AS-level, 3.5.1.6 Electromotive force and internal resistance and 3.5.1.4 Circuits. Topic: Direct Current Circuits.

Key terms in this lesson

precision
How close repeated measurements of the same quantity are to one another, shown by a small spread about the mean.
accuracy
How close a measured value is to the true or accepted value of the quantity being measured.

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