IIT JEE , AIEEE Forum - Physics , Electricity

Ank999

The internal resistance of an accumulator battery of emf 6V is 10 ohm when it is fully discharged . As the battery gets charged up , it internal resistance decreases to 1 ohm . The battery in its completely discharged state is connected to a charger which maintains a constant potential difference of 9V . Find the current through the battery
(a) Just after the connections are made
(b) After a long time when it is completely charged

plz tell what happens when a battery gets charged and discharged

cvramana

(a) The current just after the connections are made is given by

i = (9 - 6) / 10 = 0.3 amp

(b) The current after completely charging is

i = (9 - 6) / 1 = 3 amp.

Prakriteesh

Current always flows from a higher potential to a lower potential. So, the normal course of current flow is:

However, while charging, it is necessary to flow the current in the opposite direction through the battery so that the chemical reactions opposite to those in discharging (normal current flow) takes place. In order to do so, we have to provide a potential difference higher than that between the plates of the emf as shown in the following diagram:

Emf

Charger

When the internal resistance is drawn and Loop law is applied, we get the following diagram and equation:

emf , int. resist

Charger(V)

E + ir -V = 0

The rest is same as Raman sir's

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