You visited us 1 times! Enjoying our articles? Unlock Full Access!

Potentiometer

Two cells of ...

Question

Two cells of same emf E but of different internal resistance $r_{1}$ and $r_{2}$ are connected in series with an external resistance $R$ . The potential drop across the first cell is found to be zero. The external resistance $R$ is

r_{1} + r_{2}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

r_{1} - r_{2}

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

\frac{r_{1} r_{2}}{r_{1} + r_{2}}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

\sqrt{r_{1} r_{2}}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is B $r_{1} - r_{2}$
The total current in the circuit is
$I = \frac{2 E}{r_{1} + r_{2} + R}$ ..............................(1)..... $($ In series, $E + E = 2 E)$
Now the potential drop across first cell is
$V_{1} = E - I r_{1}$
As per the given condition
$V_{1} = 0$
hence,
$E - I r_{1} = 0$
$E - (\frac{2 E}{r_{1} + r_{2} + R}) r_{1} = 0$ .....................from $(1)$
$\frac{2 r_{1} E}{r_{1} + r_{2} + R} = E$
$\Rightarrow r_{1} + r_{2} + R = 2 r_{1}$
$R = r_{1} - r_{2}$

Suggest Corrections

Similar questions

Q. Two cells of same emf E but different internal resistances

r_{1}

and

r_{2}

are connected in series with an external resistance

R

. The potential drop across the first cell is found to be zero. The external resistance

R

Two cells with the same emf E and different internal resistance $r_{1} a n d r_{2}$ , are connected in series to an external resistance R. The value of R so that the pd across the ﬁrst cell is zero, is:

Q. Two cells of same emf are in series with an external resistance R. The internal resistance

r_{1}

r_{2}

. The p.d across the

1^{s t}

cell is found to be zero the value of R is

Q. Two cells having the same emf are connected in series through an external resistance

R

. Cells have internal resistances

r_{1}

and

r_{2}

such that

r_{1} > r_{2}

respectively. When the circuit is closed, the potential difference across the first cell is zero, then the value of

R

Q. Two cells, having the same e.m.f are connected in series through an external resistance R. Cells have internal resistance

r_{1}

and

r_{2}

(

r_{1}

r_{2}

) respectively. When the circuit is closed, the potential difference across the first cell is zero. the value of R is

Join BYJU'S Learning Program

Two cells of same emf E but of different internal resistance r1 and r2 are connected in series with an external resistance R. The potential drop across the first cell is found to be zero. The external resistance R is

Two cells of same emf E but of different internal resistance $r_{1}$ and $r_{2}$ are connected in series with an external resistance $R$ . The potential drop across the first cell is found to be zero. The external resistance $R$ is