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Can the potential difference across a battery be greater than its EMF?
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
How the cells of same emf can be connected to get large value of emf?
They are connected in 'series', the negative terminal of one cell connected to the positive terminal of the next cell, and so on with as many cells as you have, so that there is only one path for current through the entire combination of cells. In this configuration, the EMF of the combination is the sum of the individual EMFs, but the combination can't deliver any more current (amperes) than any single cell can.
Is potential difference always less than emf of the cell?
No. Because during charging process of a battery current flows in opposite direction to the discharging/consumption. so equation Emf=P.d. +Ir is changed to Emf=p.d. +Ir. Hence during charging process of a battery Potential difference is greater than electromotive force.
How to measure the electromotive force (EMF) of a cell accurately?
To measure the electromotive force (EMF) of a cell accurately, use a voltmeter with high precision and connect it to the terminals of the cell. Ensure the cell is not connected to any external circuit during the measurement to prevent errors. Take multiple readings and calculate the average to minimize inaccuracies.
How does the EMF of a battery which is made up of cells in series compare with the EMF of the individual cell?
The EMF of a battery made up of cells in series is equal to the sum of the EMFs of the individual cells. When cells are connected in series, their voltages add up. For example, if you have two 1.5V cells in series, the total EMF of the battery would be 3V.
Why emf of battery driving potentiometer is greater than emf of the cell to be measured?
Bcoz the emf which is to be measured is less than emf of driving cell....
How do you determine the emf and internal resistance of a cell?
You can measure the emf of a cell by using a voltmeter, as this draws current from a cell. You can use the voltage, the emf, and the load resistance to determine the internal resistance of the cell.
Can you measure the emf of a cell with a voltmeter?
you can, but you will not get accurate answer as voltmeter consumes some current. so, potentiometer is used instead to measure emf ---- the potentiometer must be set to the expected emf from the cell before you put the zero detector in circuit if its set too high it will charge the cell too low it will load the cell perhaps if you dont know the voltage of the cell before you measure it you should get a hi impedance voltmeter(electrometer) to set the potentiometer as close as you can manage before you connect the zero detector
Is free energy of cell reaction positive when emf of cell reaction is positive?
No, the free energy of a cell reaction is negative when the emf of the cell reaction is positive. This is because a positive emf indicates that the reaction is spontaneous and capable of performing work, resulting in a negative change in free energy.
Can the potential difference across a battery be greater than its EMF?
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
A voltaic cell is made of silver and gold electrodes What is the emf of this cell?
1.03 V
What is the Condition for terminal voltage across a secondary cell to be equal to its emf?
The condition for the terminal voltage across a secondary cell to be equal to its emf is when there is no current flowing through the cell. When there is no current, there is no voltage drop across the internal resistance of the cell, and thus the terminal voltage equals the emf.
A voltaic cell is made of copper and aluminum electrodes What is the emf of this cell?
The EMF of a copper-aluminum voltaic cell can be determined by the standard reduction potential of each metal. Copper has a higher standard reduction potential than aluminum, so the cell will have a positive EMF. The exact value can be determined by calculating the difference between the reduction potentials of copper and aluminum.
How the cells of same emf can be connected to get large value of emf?
They are connected in 'series', the negative terminal of one cell connected to the positive terminal of the next cell, and so on with as many cells as you have, so that there is only one path for current through the entire combination of cells. In this configuration, the EMF of the combination is the sum of the individual EMFs, but the combination can't deliver any more current (amperes) than any single cell can.
What is the emf of an electrolytic cell made with solid aluminum and silver electrodes?
-2.48
What is the emf of a voltaic cell made with solid zinc and silver electrodes?
+1.56
Why cant you use voltmeter 2 calculate emf of a cell?
A voltmeter measures potential difference across a component, which may not necessarily be equal to the EMF of a cell due to internal resistance in the cell and voltage drops across other components in the circuit. To accurately measure the EMF of a cell, a potentiometer or a high-resistance voltmeter is used in conjunction with a null point method.
