Question

a cell of EMF E1 balances a length of 150cm of potentiometer wire, another cell of EMF 2V balances a length of 300cm of wire, EMF el is O 1V O 1.5 V 2.5 V 0 v 0.1 V​

Answer 1

Answer:

Correct option is

A

1 ohm

Given,

Length of the potentiometer wirel

1

=150cm

Resistance R=5Ω

balancing length is obtained at l

2

=125cm

Internal resistance r=?

we have,

r=R[

l

2

l

1

−1]

=5[

125

150

−1]

=5[

125

25

]

=1Ω

Answer 2

Answer: 1 Volt

Explanation:

• Potentiometer is a device which is used to determine the unknown voltage by comparing it with a known voltage.
• The potentiometer works on the principal that the potential is directly proportional to the length of the wire i.e., when the length of the wire balancing the potentiometer increases the voltage also increases.
• It can be formulized as,

            $\frac{E_{1} }{l_{1} } =\frac{E_{2} }{l_{2} }$

        ⇒ $E_{1} } =\frac{E_{2}l_{1} }{l_{2} }$

        ⇒ $E_{1} =\frac{2*150}{300}$

         ∴ $E_{1} =1\ volt$

• Hence, the required EMF is 1 volt as caculated above.

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