Question

The measurement of voltmeter in the following circuit is

• A. $2.4V$
• B. $3.4V$
• C. $4.0V$
• D. $6.0V$

Answer 1

Answer: (A)

Resistance of voltmeter and $60\Omega$ are in parallel.
$\therefore$ Equivalent resistance
$=\frac{60\times 40}{60+40}=\frac{60\times 40}{100}=24\Omega$
For the whole circuit,
current $I=\frac{6V}{(40+24)\Omega }=\frac{6}{64}=\frac{3}{32}A$
The voltmeter reads potential difference across $60\Omega$.
$\therefore$ Voltmeter reading $=I\times R_{eq}$
$=\frac{3}{32}\times 24=\frac{9}{4}V=2.25V$.