In given diagram value of carbon resistor is 22 × 10 5 Ω ± 5 % . Write colour of first ring A .

According to colour code of carbon resistors, red stands for 2, yellow for 4, blue for 6 and silver stands for 5%.First and second band represents the first two significant figure of resistance. Third band represents the power raised to 10 in the value of resistance. Fourth band represents the tolerance. Given carbon resistor 22 × 10 5 Ω ± 5 % thus, Red is the colour of first ring A.

Obtain necessary condition for balancing state of Wheat Stone Bridge by using Kirchhoff's law. Draw necessary circuit diagram.

I = 0 in galvanometer branch Applying Kirchoff's law for loop ABCD A - I 1 R 1 + 0 + I 2 R 2 = 0 I 1 R 1 = I 2 R 2 I 1 I 2 = R 4 R 1 . . . . . . . . . . ( 1 ) Applying Kirchoff's law for loop BCDB - I 1 R 3 + I 2 R 4 + 0 = 4 I 1 R 3 = I 2 R 4 I 1 I 2 = R 4 R 3 . . . . . . . . ( 2 ) from equation (1) and (2), we get, I 1 I 2 = R 4 R 3 = R 2 R 1 R 4 R 3 = R 2 R 1 R 1 R 2 = R 3 R 4 Balancing condition for wheat stone bridge