Question

ABCDE is a pentagon. The potential at A is 12V, potential at B is 15V, potential at C is -11V, at E it is -17V and at D the potential is not known. What is the potential drop when you move from B to E?

Answer 1

Answer:

Resistance given here is 20 ohm

As it is bend into wire so, L = 2πr

so, Ri = Rho×2πr/A = 20 ohm

Now, resistance between two point at the end of diameter can be given by

1/R = (1/Ri/2)+(1/Ri/2) {as half of the wire is attached to the other half so it may be considered as parallel connection}

1/R = 1/10+1/10 { Ri = 20ohm so Ri/2 = 10 ohm }

or 1/R = 2/10

so, R = 5 ohm ,(across ends of diameter)

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Answer 2

Answer: Here in the pentagon a=12v , b=15v , c=-11v , d=unknown and e=-17v.
to find the potential drop here :

V (BE) = v(b) - v(e)
           =15v - (-17)v
           =(15 + 17)v
           = 32v

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