Calculating Potential Difference Between Points A and B

[mujadeo]

Homework Statement

a current of 2A is flowing from a to b.
what is the potential difference between the points?

______a______3ohm_____-20V+_____1ohm_______+6V-________b_____


hopefully my diagram makes sense.

Homework Equations

this is a really simple question and i can't answer it because I am not understanding the whole concept.
Does current (or anything) stay constant in a cicuit??
do i follow the current round/thru circuit and do calcs along the way?
so voltage after 3ohm-R = IR = 6V
so 6V into 20V battery. now I am stuck. it goes into neg term first so is that -20V?? please help somene! thanks

The Attempt at a Solution

 

[rl.bhat]

If you assume a battery of EMF E volt is connected across the a and b such that a end is +ve and b end is -ve. Apply loop law, and find E. If you get E +ve, signs of a and b correct. If you get E -ve, reverse the signs of a and b.

 

[ogb p]

As a scientist, it is important to understand the concept of potential difference and how it relates to current flow in a circuit. In this scenario, we have a current of 2A flowing from point A to point B. The potential difference between two points is defined as the work done per unit charge in moving from one point to the other. In simpler terms, it is the energy required to move a unit of charge between two points.

In this case, we can calculate the potential difference between points A and B by using Ohm's Law, which states that the potential difference (V) is equal to the current (I) multiplied by the resistance (R). In the diagram provided, we can see that there is a 3ohm resistor between points A and B, followed by a 20V battery, and then a 1ohm resistor.

To calculate the potential difference between points A and B, we can start by calculating the voltage drop across the 3ohm resistor. Using Ohm's Law, we can see that the voltage drop is equal to 2A (the current) multiplied by 3ohms (the resistance), which gives us a voltage drop of 6V.

Next, we can calculate the total voltage of the battery by adding the voltage drop of 6V to the initial voltage of -20V, giving us a total battery voltage of -14V.

Finally, we can calculate the potential difference between points A and B by adding the voltage drop of 6V to the battery voltage of -14V, giving us a total potential difference of -8V. This means that the potential at point B is 8V lower than the potential at point A.

To answer your question about whether current stays constant in a circuit, the answer is no. In this scenario, the current is 2A because that is the current being supplied by the battery. However, as the current flows through the circuit, it may encounter resistances that can change the current. This is why we use Ohm's Law to calculate the voltage drop across each component in the circuit, so we can understand how the current is affected.

I hope this explanation helps you understand the concept of potential difference and how it relates to current flow in a circuit. If you have any further questions, please don't hesitate to ask.