# A source of potential difference V volt sends current I ampere in a circuit for time t second. Write expressions for electrical energy supplied by the source and electrical power spent by the source. - Physics

Sum

A source of potential difference V volt sends current I ampere in a circuit for time t second. Write expressions for

1. electrical energy supplied by the source and
2. electrical power spent by the source.

#### Solution

Potential difference V is the work done in moving a unit charge

∴ Work was done in moving a charge Q through the pot. diff. V = QV

i.e. W = QV

but = "Q"/"t" = "I" or Q = It

∴ W = VIt

Work done = Electrical energy

(a) ∴ Electrical energy = VIt is the expression

(b) Power is the rate of doing W

P = "W"/"t" = "VIt"/"t" = "VI"

P = VI is the expression.

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#### APPEARS IN

Selina Concise Physics Class 8 ICSE
Chapter 8 Electricity
Exercise 8 (A) (Short/Long answer questions) | Q 8 | Page 151
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