Question

In the Kelvin’s method, balancing point is obtained 40cm from right end. If resistance in the right gap is 60Ω, resistance of galvanometer is;

Answer 1

It has given that, in a Kelvin method, balancing point is obtained 40 cm from the right end. If the resistance in the right is 60Ω.

We have to find the resistance of galvanometer.

Solution : we know, in Kelvin method, in one gap, galvanometer is attached while in other gap, a resistor is attached.

At balance condition,

Resistance of galvanometer/resistance of resistor = length of wire opposite to the galvanometer/length of wire opposite to the resistor

i.e., G/R = L₁/L₂

Here L₂ = 40 cm so L₁ = 100 cm - 40cm = 60cm and R = 60Ω

So, G/60 = 60/40

⇒G = 60 × 3/2 = 30 × 3 = 90Ω

Therefore resistance of galvanometer is 90Ω

Answer 2

GivEn :-

• Kelvin’s method, balancing point is obtained 40cm from right end. If resistance in the right gap is 60Ω

To FinD :-

• Resistor of the Galvanomter.

CalculaTioN :-

According tk the Kelvin's Method in a gap galvanometer is attached and at the same time in other gap a resistor is attached.

★ At Balance Condition.

Ressistor of Galvanometer / Resistance of Resistor = Length of the wire opposite to the Galvanometer/ Length of wire opposite to the Resistor. R

Which is,

$\sf{ \frac{G}{R} = \frac{L1}{L2} }{}$

Here L2 = 40cm so, L1 = 100cm - 40cm = 60cm and R = 60Ω

So,

• G/60 = 60/40

• G = 60 x 3/2 = 30 x 3 = 90Ω

$\boxed{ \bold{ \red{★Hence \: R \: of \: galvanometer =90Ω} }{} }{}$