question_answer

An ideal ammeter and an ideal voltmeter are connected as shown. The ammeter  and  voltmeter  reading  for  the  circuit  having\[{{R}_{1}}=5\Omega \],\[{{R}_{2}}=15\Omega \],\[{{R}_{3}}=1.25\Omega \]and\[E=20\]V are given as

A)  6.25 A, 3.75 V   

B)  3.00 A, 5 V

C)  3.75 A, 3.75V    

D)  3.75 A, 6.25 V    

Correct Answer: B

Solution :

 \[{{R}_{eq}}\]of the circuit\[\frac{{{R}_{1}}\times {{R}_{2}}}{{{R}_{1}}+{{R}_{2}}}+{{R}_{3}}\] =\[\frac{5\times 15}{5+15}+\frac{125}{100}\] \[=\frac{75}{20}+\frac{5}{4}=5\Omega \] \[l=\frac{E}{{{R}_{eq}}}=\frac{20}{5}4A\] Current in\[{{R}_{1}}=\frac{l{{R}_{2}}}{{{R}_{1}}+{{R}_{2}}}=3\]A Potential difference across R\[{{R}_{3}}=l{{R}_{2}}=5\]V