Wheatstone Bridge Principle states the if four resistance P, Q,
R and S are arranged to form a bridge as shown in figure with a cell E and one
key K1 between the point A and C and galvanometer G and tapping key K2
between the points B and D, closing K1 first and K2 later
on, if the galvanometer shows no deflection then bridge is balanced.
Current distribution in the circuit is shown in the figure. Total
current by cell is I, it distributed to P and S as I1 and I-I1.
Let current through galvanometer is Ig.
Current in Q is I1-Ig and in S
current are I-I1+Ig. Resistance of galvanometer is G.
Now apply Kirchhoff’s 2nd law in ABDA, we get
I1P +Ig G – (I-I1) R=0 …..…1
Now apply Kirchhoff’s 2nd law in BCDB, we get
(I1 –Ig) Q – (I-I1+Ig)
S – Ig G = 0 …….2
If value of R is such that the galvanometer shows no deflection
that is Ig = 0. Putting this value in equation 1 and 2 we
get
This last equation relating the four resistors is
called the balance condition for the
galvanometer to give zero or null deflection.
A practical device using this
principle is called the meter bridge.
sir, your notes are still helping. i am doing aerospace engineering from amity university. URVASHI PUNDIR
ReplyDeleteoohh...that is really very nice ....Aerospace Engineering was my dream.....good...keep doing good work.
DeleteRegards
DMR
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DeleteSir, could you explain How is the Wheatstone principle used in a meter bridge to find out an unknown resistance? Your notes were very helpful though. I'm doing 10th Grade CBSE. Please help ASAP. :)
ReplyDeleteHi Mohit,
DeletePlease refer this link:
http://dmr-physicsnotes.blogspot.in/2013/01/slide-wire-bridge-or-meter-bridge.html
Regards
DMR
Thank you sir
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Explain the uses of wheat stone bridge in detail .
ReplyDelete