Problem on Circuits

Q. What is the current through the 8 ohms resistance connected across terminals M and N in the circuit as shown in below figure.

A)0.34 A from M to N.

B)0.29 A from M to N.

C)0.29 A from N to M.

D)0.34 A from N to M.

Solution :-

We have to redraw the circuit as shown in below figure

Apply KCL at node Vo,we get

((Vo+8)/12)+(Vo/8)+((Vo+2)/8)=0

(Vo/12)+(Vo/8)+(Vo/8)= - [(8÷12)+(2÷8)]

Vo[(1/12)+(1/8)+(1/8)]= - 0.916

=> Vo(0.333)= - 0.916

=> Vo = - (0.916÷0.333)

=> Vo = -(2.75). Volts

Vo is the voltage across M and N ,

Current I at the 8 ohms resistor is,

I = Vo/ Resistance at 8 ohms

I=(-2.75)÷8

I= - 0.34 Amperes

The current between M and N is - 0.34 Amperes

Now we have to interchange the terminals we can get positive current .

i.e., the current 0.34 A current flows from terminal N to terminal M .

Ans is option D.

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Electrical Engineering