Question

$A,B$ and $C$ are voltmeters of resistance $R,1.5R$ and $3R$ respectively. When some potential difference is applied between $X$ and $Y$, the voltmeter readings are $V_A,V_B$ and $V_C$ respectively. Then

• A. $V_A=V_B=V_C$
• B. $V_A\ne V_B=V_C$
• C. $V_A=V_B\ne V_C$
• D. $V_A\ne V_B=V_C$

Answer 1

The correct option is A $V_A=V_B=V_C$

We know that in parallel combination voltage remains same.
Thus,$V_B=V_C$
We can easily eliminate options (c) and (d) from this
Resistances $1.5R$ and $3R$ are connected in parallel so their equivalent resistance can be given by
$R_{eq}=\frac{1.5R\times 3R}{1.5R+3R}$
$⟹R_{eq}=R$
This combination of voltmeters $B$ and $C$ is in series with voltmeter $A$.
Due to same current passing through them, voltage drop across resistances $R$ and $R_{eq}$ will be same.
$⟹V_A=V_B=V_C$