Determine the principal and working al metre
bredge with the help of a circuit diagram
Answers
Answer:
Meter Bridge:-
An electrical instrument based on the wheat stone bridge which is used for measuring the unknown resistance of any material is called as meter bridge.
It consists of a wire whose length is one meter and has uniform cross-sectional area.
Meter bridge works on the principle of Wheatstone bridge. Here, we need to find the unknown resistance 'S'.
Here, length of meter bridge wire =l=1m=100cm (given)
When the pointer C is moved along AB such that there is so current in Galvanometer (G). This Wheatstone bridge arrangement which is down to the right side of the diagram
According to Wheatstone bridge principle :-
R
AC
R
AD
=
R
BC
R
BD
⇒
R
AC
R
=
R
BC
S
....(1)
R
AC
=
A
ρl
AC
=
l
R
o
×x=(
l
R
o
x
)
For R
BC
;−l
BC
=(100−x)
R
BC
=(
A
ϱl
BC
)=
l
R
o
×(100−x)
R
BC
=
l
R
o
(100−x)
Put value of R
AC
and R
BC
in equation (1)
⇒
R
AC
R
=
R
BC
5
⇒
(
l
R
o
x
)
R
=
l
R
o
(100−x)
S
⇒
x
R
=
100−x
S
⇒S=
x
R
×(100−x)
S=
x
R(100−x)
Here, S is unknown
R is known
This is the required formula to find unknow resistance value S.
solution