Voltage drops over a Circuit

[james11223]

Homework Statement

Show that the voltage drops over the circuit is 0. What is the voltage at B?

Homework Equations

I = E/Req

The Attempt at a Solution

120V/120ohms = 1 A

120V - (80*1) - (10*1)- (30*1) = 0

120 - 80 - 10 = 30V at B

I have nooo idea about the B part... can someone please verify!

THANKS!

 

[gneill]

You seem to have done all right.

The question is a bit sloppy though: they should have specified a point of reference when they asked about the voltage at node B. The default assumption in this case is to reference the "-" terminal of the supply.

 

[james11223]

So in my understanding the current is flowing clockwise... is that a correct assumption?

 

[gneill]

So in my understanding the current is flowing clockwise... is that a correct assumption?

The battery symbol in the schematic implies that it is "+" on top, so yes, conventional current flow would be clockwise in the circuit.

 

[rwisz]

I would like to clarify that voltage drops over a circuit are a result of the resistance in the circuit. In an ideal circuit with no resistance, there would be no voltage drop. However, in real-world circuits, there will always be some amount of resistance, resulting in a voltage drop. In the given circuit, the total resistance is 120 ohms, which is why the voltage drop is 120V. The voltage at point B can be calculated using Ohm's Law, which states that voltage (V) is equal to current (I) multiplied by resistance (R). Therefore, the voltage at point B would be equal to the current (1A) multiplied by the resistance (30 ohms), resulting in a voltage of 30V at point B. It is important to note that the voltage at point B is not equal to 0, as there is still some resistance in the circuit. I hope this helps clarify any confusion.