project to study various factors on which the internal resistance emf of a cell depends

Emf

• Potential difference between the two poles of the cell in an open circuit is calledemfof the cell.

SI unit is volt (V).Internal resistance (r) of cell

• Resistance offered by the electrolyte of the cell when the electric current flows through it

Eemfof cell

r Internal resistance of the cell

R External resistance

K Key

V Voltmeter

• The keyKis closed and a currentIflows in the circuit.

According toOhms law,

• LetVbe the terminal potential difference. The terminal potential difference V is less thanemfE of the cell by an equal amount, which is equal to potential drop across external resistance R i.e.,

∴V=EIr

Also, terminal potential difference is equal to potential differences across external resistance.

V=IR

From equation (1),