Question

Q. 19
PHYSICS
CHEMISTRY
BIOLOGY
MATHS
Resistances of 90 and 61 are connected as shown in the figure below. A 6 volt supply source is connected across P and Q.
The reading of ammeter (shown in figure) is obtained Z milli-ampere. Find value of Z.
6.2
W
922
w
90
692​

Answer 1

ANSWER

Voltage drop across voltmeter is 3 V and emf is 4 V.

Hence, voltage across A

I

is 1 V.

Hence, resistance of ammeters is 100 Ω.

Let the potential of the point of intersection of the 100 Ω resistances and A

II

be x.

Using KCL:

$100</p><p>x−4</p><p> </p><p> + </p><p>100</p><p>x</p><p> </p><p> + </p><p>100</p><p>x−1</p><p> </p><p> =0</p><p></p><p>3x=5 </p><p></p><p>⇒x= </p><p>3</p><p>5</p><p> </p><p> </p><p></p><p>Hence, current in A </p><p>II</p><p> </p><p> = </p><p>100</p><p>x−1</p><p> </p><p> = </p><p>300</p><p>2</p><p> </p><p> =6.67 mA$