Question

Two diametrically opposite points of a metal ring are connected to two
terminals of the left gap of meter bridge. In the right gap, resistance
of 15 is introduced. If the null point is obtained at a distance of 40
cin from the left end, find the resistance of wire bent in the shape of
ring.​

Answer 1

Answer:

r = 20 Ω

Explanation:

Here we will use the principle of meter bridge

So,  

P/Q= R/S

where,  

P = 40 ρ

Q= 60ρ

S= 15Ω

R=10Ω              

Now, two points are connected to the diameter of a ring.Therefore we have two parallel path.

If the resistance of both the path is  r

Then equivalent resistance  = r/2

r/2 = 10

r = 20 Ω  

Answer 2

Hence the resistance of the wire is 20 Ω

Explanation:

By using the principle of meter bridge

So, Q P  =  S R

​Where

P=40ρ     [ρ is resistance/unit length]

Q=60ρ

S=15 Ω

R=10 Ω

• Now, two points are connected to the diameter of a ring.
• Therefore we have two parallel path.
• If the resistance of both the path is r

Then equivalent resistance =   r / 2  ​= 10

r = 20 Ω

Hence the resistance of the wire is 20 Ω