JEE Main | 2018Current Electricity and Electrical InstrumentHard

Question

In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across 52 cm of the potentiometer wire. If the cell is shunted by a resistance of 5Ω, a balance is found when the cell is connected across 40 cm of the wire. Find the internal resistance of the cell.

Options

A.

1.5 Ω

B.

2 Ω

C.

2.5 Ω

D.

1 Ω

Solution

without shunting condition :

Es = 52 ×x ...(1)
when balanced
where, x = potential gradient of wire.
with shunting condition

On balancing
Es-Es(r+R)r=40 × x   ....(2)
On solving :
(1)(2)⇒11-rr+R=5240  ∴ r = 1.5Ω

Create a free account to view solution

View Solution Free
Topic: Current Electricity and Electrical Instrument·Practice all Current Electricity and Electrical Instrument questions

More Current Electricity and Electrical Instrument Questions

Figure shows a thick copper rod X and a thin copper wire Y, joined in series. They carry a current which is sufficient t...Two wires of resistance R1 and R2 at 0o C have temperature coefficient of resistance a1 and a2, respectively. These are ...A potential difference V is applied across a copper wire of diameter d and length L. when only d is doubled, the drift v...A wire of length L and 3 identical cells of negligible internal resistances are connected in series. Due to the current,...Assertion :- [Pt(trien)]+2 is more stable complex cation than [Pt(en)2]+2. Reason :- Trien is a chelating ligand....