Question

A potentiometer wire 10m long and having 20 resistance is connected in series with a battery and a resistance R =
21600. A Daniel cell of emf 1.08 v is balanced across the P.D of the resistance R. The emf of thermo coupled is balanced
across 300 cm of the wire. The emf of thermo couple is
(A) 2 mv
(B) 4 mv
(C) 3 mv
(D) 1 mv​

Answer 1

Answer:

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Asked on December 27, 2019 by

Shruthi Verma

A potentiometer wire of 10m length and 20 ohm resistance is connected in series with a resistance r ohms and a battery of emf 2V, negligible internal resistance, Potential gradient the wire is 0.16 millivolt/centimetre then r is ohms:

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ANSWER

Given that,

Resistance of the wire R=20 Ω

Potential meter length L=10 m

e. m. f E=2 volt

Potential gradient K=0.16 mv/cm

Now, the current is

I=

R+r

E

Potential across the wire is

V=IR

V=

R+r

ER

Potential gradient is

K=

L

V

K=

L(R+r)

ER

....(I)

Now, put the all values in equation (I)

0.016=

10(20+r)

2×20

3.2+0.16r=40

0.16r=40−3.2

0.16r=36.8

r=

0.16

36.8

r=230Ω

Hence, the value ofr is 230 Ω.

Answer 2

Explanation:

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