Question

A wire of unifonn cross-section is bent in the

shape of a complete ring. Two diametrically

opposite points on the wire are connected to the

two terminals of left gap of a metrebridge. The

resistance of 15 n is connected in the right gap.

If the null point is obtained at 70 em from the

left end of the bridge wire, find the resistance of

the wire before bending it to a ring. ​

Answer 1

Answer:

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Here we will use 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 =

2

r

2

r

=10

r=20 Ω