How to measure potential difference between two points #6

Описание: When you attempt problems around circuits, you need to find the potential difference between two points. This lesson explains the steps you can use to calculate the potential difference between points a and b.
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At a basic level, we start at point “a” where the potential is Va, and as we move up towards b, we add up all gains and losses in potential.

Also in this lesson, power from batteries. Batteries form part of most circuits. So when a battery establishes current by doing work on a charge carrier what is happening is that the chemical energy of the battery is getting transferred to the charge that enables it to move in the circuit and create current. And since any emf device, like a battery here, would have an internal resistance, some energy would get wasted there.

Well we know that the useful power a battery can generate is iV where V is the terminal PD and I is the current in the circuit. The terminal potential difference is the emf value less the potential drop across the internal resistance of the battery.

Topics covered in this lesson-

00:45 Potential difference between point a and b
03:30 Work done by battery on a charge
03:30 Power generated by a battery
04:15 Solved practice problem
04:35 What is the current in the circuit
06:05 What is the potential difference between terminals of a battery

Transcript

Often when you attempt problems around circuits you are asked to find the potential difference between two points. In this lesson let us learn that and we will do so by taking a simple circuit and establishing the potential difference between any two randomly chosen points.

To find the potential difference between any two points, start at one point and move in the circuit toward the other point, and add all changes in potential algebraically. This would be the potential difference between the two points

A battery generates current by doing work on a charge, and so the chemical energy of the battery is transferred to the charge enabling it to move and generate current. But not all energy from the battery is available to move the charges, part of it is wasted in the internal resistance. So let us find the relationship between power, current and emf

The power a battery generates is iV, and V here is emf less the potential loss in internal resistance … if we put the value of V in this equation, what we get is this

Then this term is the rate of thermal energy loss in the internal resistance r, lets call it Pr

And therefore, this should be the total rate of energy generated by the battery and transferred to the charge carriers and the internal resistance of the battery