What is the equivalent resistance between points a and b in

What is the equivalent resistance between points a and b in the figure shown below If the potential difference between a and b is 10 volts, what is the power dissipated across the 4 Ohm resistor

Solution

A)

Equivalent resistance across a and B :

Rnet = 5 + ( 12 || 6 || 4 ) + 3 < --- NOTE: The 50 ohm has been shot circuited and thus is not included in the calculation.

= 5 + 1/(1/12 + 1/6 + 1/4 ) + 3

= 10 ohms <------- answer

B)

So, net current in the circuit: = 10V / 10 ohms

= 1 A

So, voltage drop across 4ohm resistor = 10 - 1*(5+3) = 2 V

So, power dissipated across 4ohm = 2^2/4 = 1W <------ answer