Question

The diagram shows a cell connected in series with an ammeter and three resistors (10 Ω, 20Ω, 30Ω). The circuit can be completed by a movable constant M. When M is connected to x, then ammeter reads 0.6 A. what is the ammeter reading when M is connected to y?

Answer 1

The current when it is connected to x is 0.6 A, so net resistance is 10 ohms so the cell voltage is 10 × 0.6 = 6 V. 

Now when M is connected to y 

The net resistance is sum of the resistance of 10 Ω and 20 Ω 

R_net = 10 + 20 =30 Ω 

As we know by ohms law,

V = I R 

Putting the values in the equation, we get

6 V = I x 30 Ω

I = \(\frac{6}{30}\) 0.2 A.

Thus, the reading of ammeter is 0.2 A.