Question

Draw a neat labelled diagram to determine the resistance of a galvanometer by using metre bridge.​

Answer 1

Given:

A metre bridge has been provided.

To find:

Resistance of a galvanometer?

Calculation:

Here , in the diagram, we can one more modification:

• We will add a known galvanometer to the movable wire , so that we can see if current passes through the wire or not !

Now, let galvanometer resistance be G.

Steps:

• We will keep on moving the wire and touch it to various length of the 100 cm wire and see the position when there is no deflection in the known galvanometer.

• That position is the Balanced WHEATSTONE BRIDGE point.

Let the left gap length be l_(g) and right gap is l_(r):

$\therefore \: \dfrac{G}{R} = \dfrac{l_{g}}{l_{r}}$

$\implies\: \dfrac{G}{R} = \dfrac{l_{g}}{100 - l_{g}}$

$\implies\: G = \bigg( \dfrac{l_{g}}{100 - l_{r}} \bigg)\times R$

This is how resistance of Galvanometer can be ascertained.

Answer 2

Given:

A metre bridge has been provided.

To find:

Resistance of a galvanometer?

Calculation:

Here , in the diagram, we can one more modification:

We will add a known galvanometer to the movable wire , so that we can see if current passes through the wire or not !

Now, let galvanometer resistance be G.

Steps:

We will keep on moving the wire and touch it to various length of the 100 cm wire and see the position when there is no deflection in the known galvanometer.

That position is the Balanced WHEATSTONE BRIDGE point.

Let the left gap length be l_(g) and right gap is l_(r):

\therefore \: \dfrac{G}{R} = \dfrac{l_{g}}{l_{r}} ∴

R

G

=

l

r

l

g

\implies\: \dfrac{G}{R} = \dfrac{l_{g}}{100 - l_{g}} ⟹

R

G

=

100−l

g

l

g

\implies\: G = \bigg( \dfrac{l_{g}}{100 - l_{r}} \bigg)\times R⟹G=(

100−l

r

l

g

)×R

This is how resistance of Galvanometer can be ascertained.