a) use kirchhoff's rules , calculate the current in the arm AC of the given circuit. (b) on what principle does the metre bridge work? why are the metal strips used in the bridge ?

Question

​
a) use kirchhoff's rules , calculate the current in the arm AC of
the given circuit (b) on what principle does the metre bridge work?
why are the metal strips used in the bridge ?​

Vaibhav T. · Accepted Answer

Dear Student,

(a)
<img src=
"https://s3mn%20mnimgs%20com/img/shared/content_ck_images/ana_qa_image_57b2eda512137%20png">

Applying kirchoff's junction rule at A node,I3=I1+I2  
(1)Applying kirchoff's second rule in loop EFCA,-30I1+40-40I3=0  3I1+4I3=4 
(2)In loop EFDB,-30I1+20I2-80=0-3I1+2I2=8 
(3)from equation (1) put the value of I3 in equation (2),3I1+4I1+I2=47I1+4I2=4  
(4)from (3) and (4),13I1=-12I1=-1213 APut I1 in equation (4),7×-1213+4I2=44I2=4+8413I2=3413 Afrom equation (1),I3=-1213+3413I3=2213 A

(b) Metre bridge works on the principle of Wheat stone bridge The
thick metal strips are used to minimise the
resistance of connection wires, because the connection resistance
have not been accounted in the formula (resistance is inversely
proportional to cross section area, so thick wire has low
resistance, moreover the resistivity of copper is small compared to
manganin

​ a) use kirchhoff's rules , calculate the current in the arm AC of the given circuit. (b) on what principle does the metre bridge work? why are the metal strips used in the bridge ?​

a) use kirchhoff's rules , calculate the current in the arm AC of the given circuit. (b) on what principle does the metre bridge work? why are the metal strips used in the bridge ?