Question

Figure shows a circuit in which the potential differences across the resistance are given in the diagram. If point Q is grounded, then the potential at point S will be

• A. $10\text{V}$
• B. $-10\text{V}$
• C. $40\text{V}$
• D. $-40\text{V}$

Answer 1

The correct option is D $-40\text{V}$

As we know that the Ohm's law, $V=iR$

$80=i\times 80$

$i=1\text{A}$

As Q is grounded potential drop at Q is $0$

Therefore, potential difference between Q and S is calculated using KVL as,

$0-15\times 1-25\times 1=V_{\text{S}}$

$V_{\text{S}}=-40\text{V}$