# Electromotive Force Definition for Induced Current

If in DC , Emf is the work done to carry a unit positive charge from -ve to +ve terminal .

What is induced EMF then , in a similar sense ? To carry a unit charge around a loop once along a fixed circuit ? Where is a -ve to +ve place ?

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Induced emf is not totally different. But, it's somewhat different because it's very unlikely to say that it is the work done in moving an unit charge from one circuit to another (which actually happens in electromagnetic induction). Instead, it can be said as inferred by Faraday. Whenever there's a change in the magnetic flux along the circuit, there's an induced emf. The motion of electrons along a loop produces magnetic lines of force which influences another loop placed nearby. The sudden change in the emf (rise or fall) can induce an emf in the secondary circuit. The emf induced on the other loop is the induced emf and it's the voltage along that loop. $$e=-N\frac{d\phi}{dt}$$