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ELECTROMOTIVE FORCE (emf)
>The emf of a cell is the potential difference between terminals when the switch is open.
>Any source of emf is made up of non perfect material elctricity conductors. They therefore offer some resistance to the flow of current they themselves generate.
>The potential drop across the external resistor is smaller than the emf itself because of the internal resistor (r).
The voltage drop across the internal resistor is given as follows
V=Ir
E.M.F=IR
E=IR + Ir
IR is the terminal voltage
Ir is the lost voltage
If E=IR + Ir
Then E= I(R + r)
I (current)= E/R + r = I(R + r)/(R + r)
So I= E/(R + r)
Sally the guru answered the question on June 5, 2020 at 12:31
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