Test: EMFs & Internal Resistance - NEET MCQ

a car battery of 12V provides a current of about 200A, which is the current needed to operate a starter motor. So a battery has a very small internal resistance.
also,The cause of non-correctable battery problems and.A weak cell holds less capacity and is discharged more quickly.

The correct option is C

since it requires a current to be observed

It can be calculated from current and voltage data measured from a test circuit containing the battery and a load resistor 

EMF is equal to potential difference between plates when the battery is not connected to any external circuit. 
Potential difference is due to the charge accumulation on the plates. So, EMF produces a potential difference between the two terminals which drives the current.

The unit for electromotive force is Volt.
EMF is numerically expressed as the number of Joules of energy given by the source divided by each Coulomb to enable a unit electric charge to move across the circuit.
Volts=Joules/Coulombs

The maximum current can be drawn from a cell if the external resistance R = 0.

When current is to be drawn at max then the conducting wire rating comes high such that resistance is less.

Resistance R = rho x l/a

Rho = resistivity constant

L=length

a=area of cross-section

Hence, if the area of cross-section increases resistance decreases by increasing the rate of current to flow.

The internal resistance of the cell can be obtained from the relation,
I=ε/R+r
0.2=2.5/(10+r)=2.5ohm

Current provided by a battery is maximum when internal resistance is equal to external resistance. As a battery discharges, not only does it diminish its internal store of energy, but its internal resistance also increases (as the electrolyte becomes less and less conductive), and its open-circuit cell voltage decreases (as the chemicals become more and more dilute). The most deceptive change that a discharging battery exhibits is increased resistance.

as the maximum current that can be drawn from a cell is for R =0 therefore, it is I = E/r.

An open circuit implies that the two terminals are points that are externally disconnected, which is equivalent to a resistance R=∞ . This means that zero current can flow between the two terminals, regardless of any voltage difference.