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emf is present mainly in battery and potential difference is mainly present in circuit. emf is greater than p.d and p.d is greater than emf.......the units of both are Volt.....
"Potential difference" or "Voltage".
If the emf of a battery is E Volt, the potential difference across a battery is given byV = E -I r where I is the current in the circuit and r is the inetrnal resistance.Hence E and V will be equal only when I = 0.The maximum potential difference across the battery will be equal to E only if I = 0.In gnereral potential difference can be equal or less than the emf.E.m.f can never exceed the potential difference.=====================================A battery charger is a device used to put energy into a secondary cell or (rechargeable) batteryby forcing an electric current through it.Hence to charge a battery another source of emf is needed.The combined emf is now will be (E - E1) where E is the emf of the battey in quesiton and E 1 is the emf of the external source used to charge the battery.Note that E-E1 will be negative in sign.======================================...A battery is charged only when its emf is less than its maximum emf.Suppose that the maximum emf of a cell is 1.5V. The battery should be charged only when its emf is less than 1.5 V say 0.5 V.To charge the cell we use a different source of emf E1 say 3V.The positive of the second source is connected to the negative of the cell so that theCombined emf is now 0.5 - 3 = -2.5V.The negative sign indicates that the emf is opposite to the emf of the cell which is 0.5V.Since the cell is getting charged, the difference in emf is gradually reduced to zero when the cell is fully charged.In modern charging units there are provisions so that the cell is never allowed to be over charged, even if the charging unit is in on for about 12 hours.When the cell is fully charged, (that is when the emf of the cell is now 1.5V), the potential difference between either the second source or cell will be zero.Taking into consideration the sign of the emf and the direction of current through the cell and the sign of the potential difference, the potential difference will be always less than the emf of the cell (which gradually increases while charging).Note that the potential difference is negative if the emf of the cell is taken as positive.Also note that the cell is charged only when its emf is less than its maximum e.m.f
Potential or Electromotive Force (EMF).
Say 'emf' instead potential difference. Because while measuring the same no current is drawn and just balancing the potential across with the potential drop on the balancing length of the potentiometer wire. While balancing the galvanometer shows null deflection. So no current flows through the galvanometer. A perfect balance with the potential difference (EMF) of a cell with potential drop across that particular length.
yes indused emf is also called motional emf. If an open coil is subjected to a variable magnetic field, at the ends of the coil a potential difference is induced which is called induced emf. If a coil is connected to an emf source and switched on, the rising current will produced an variable magnetic field which in turn produces an emf. It is called back emf.
EMF is electromotive force. It is another name for voltage. Voltage is electric potential in joules per coulomb. Current is electric flow, in amperes. Amperes are coulombs per second. Voltage and current are not the same thing, and "emf current", or "voltage current" does not make sense.
The emf of a batter as it is used will stay the same.
When it is being loaded.
It is also called back EMF. Back EMF is the electric potential difference that opposes the current that induces it. See related link below.
yes..only the application is different.
Yes, that is what it is called.