Question

Define electric power. An electrical device of resistance R is
connected across a source of voltage V and draws a current I.
Derive an expression for power in terms of current and resistance.
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Answer 1

Answer:

• Electric power of an electrical appliance is the rate at which it consumes energy.

Let 'q' be the charges passing through the resistance R in time 't'. The work done is doing so is,

W = qV where 'V' is potential difference applied

• But q = I × t and V = IR

Therefore,

➞ W = (It) (IR)

➞ W = I²Rt

➞ W/t = I²R

➞ P = I²R (∵ P = W/t)