Emf: Emf is defined as work done per unit charge in taking a positive charge through the complete circuit ( the circuit outside the source (cell) and inside of the source. emf is represented by greek letter ε
If W is the work done when a test charge of q0 is taken through the complete circuit of a cell with a external resistance or lamp etc. Then emf of the cell is : ε=W/q0
For detail watch the video.
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