For the circiut shown in the figure, I=0.50 A and R=12 ohms. What is the value of the emf [Solved]

http://session.masteringphysics.com/problemAsset/1

It is neither series or parallel. It is a 2 mesh circuit or a 1 node.
We know the 2 24 resistors are in parallel with each other and must have the same voltage (both of their ends are connected to each other). We know the voltage across the top right 24 must be 0.5*24 = 12V so the vertical 24 also has 12V. That means there must be 0.5A down into the vertical 24 resistor. This means there must be 0.5 0.5 = 1A from left to right through the 12 resistor. That 1A divides in half at the junction of the 2 24 resistors which makes sense since it sees 24 in each path. The KVL around the left loop in a clockwise direction is
E 12V 12V = 0 => E = 24V
OR we could see there are 2 24 in parallel in the right loop = 12. Thus E sees 12 12 = 24 and there is 1A out of E so E = 1A*24 = 24V
OR we could solve using a single node V just above the vertical 24:
(V-E)/12 V/24 V/24 = 0 But we know V = 0.5A*24 = 12V (bottom of circuit chosen to be ground) so set V = 12
(12-E)/12 12/24 12/24 = 0
12/12 12/24 12/24 = E/12
12 6 6 = E = 24V

This post is last updated on hrtanswers.com at Date : 1st of September – 2022