Question

If all meters are ideal and the reading of the voltmeter $3$ is $6V$ , then power supplied by the voltage source is

• A. $10W$
• B. $38W$
• C. $20W$
• D. $30W$

Answer 1

Answer: (D)

Current through $20\Omega =\frac{6}{20}$
current through $10\Omega =\frac{6}{10}$
Total current supplied by voltage source
$=\frac{6}{10}+\frac{6}{20}$
$=0.9\text{ A}$
The voltage across voltmeter 4 = $0.9\times 30=27V$
Voltage of battery $=6+27=33volt$
Power supplied $=\frac{9}{10}\times 33$
$=29.7or30W$ ( Approx )