The potential difference (VA-VB) between the points A . . .

Question : The potential difference (V_A-V_B) between the points A and B in the given figure is

a)-3V

b)+3V

c)-13V

d)+13V

Note : There is a misprint in the figure. Actually the direction of current in not shown. You must take it from A to B.

Doubt by Jayant

Solution :

V_A-V_B = ?

I = 2A

Applying Kirchhoff's Voltage Law

V_A-2I-5-2I-V_B=0

V_A-2(2)-5-2(2)-V_B=0
V_A-4-5-4-V_B=0

V_A-13-V_B=0
V_A-V_B=13

∴ V_A-V_B=+13 V

Hence, d) would be the correct option.

Note : Because the current is flowing from A to B it indicates that potential at A (V_A) must be greater than potential at B (V_B). So V_A-V_B=+ve

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