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How to measure potential difference between two points

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. 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 __________________________________________________________________________________________ PDF Summary file: Electric Potential Playlist: https://youtube.com/playlist?list=PLQ... The Science Cube Subscription: https://the-science-cube.teachable.com/ __________________________________________________________________________________________ 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 ABOUT THE SCIENCE CUBE The Science Cube is a channel dedicated to making concepts in physics easier for any student, be it one preparing for IIT JEE or NEET or an AP physics student. #potential_difference #IITJEEpreparations #jeestrategies #JEEMain2021 #jeemains2021

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Ohm's law and power in electric circuits #3

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In this lesson we will cover what is electric current. We will also study how it is different from current density. Electric current is like a river, well almost. The definition of electric current is the rate of flow of electric charge through a conducting material. It can be written as dq/dt where dq is the charge passing through a point in time dt. Thus any forward motion of charge constitutes current. To move charges, we apply a potential difference or voltage between the ends of a conducting material and produce an electric field. This electric field makes the charges move forward and create electric current. The speed at which electrons move forward is called the drift velocity. The direction of conventional current is always opposite to that of the direction of electrons. The units of electric current are Ampere. Current density is the value of current divided by the area through which it flows. Current density is denoted by the symbol J and the formula for current density is I/A or current by the area of cross section. Topics covered: 00:18 What is electric current? 01:10 When does current flow? 01:51 Direction of motion of charges 02:20 Force on a charge 03:27 What is drift velocity 05:40 What is direction of conventional current 06:36 Definition of electric current 08:11 Derivation of drift velocity 10:20 What is charge density?

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What are unit vectors i, j and k? (what are unit vectors used for) #3

Unit vectors are any vectors that have a magnitude of one and could be pointing in any direction. These are often denoted in i,j and k form.

Such vectors are used to specify directions and therefore do not have any dimension or unit like other vectors (e.g. m/s for velocity or m/s (sq) for acceleration) The unit vectors in the positive direction of x, y and z axis are labelled as i,j and k respectively with a small hat on top.

They are used to express other vectors by combining the magnitudes of those vectors with i,j and k. Example a vector V having magnitude “a” in x direction and magnitude “b” in y direction can be written as Unit vectors are often chosen to form the basis of a vector space. Every vector in the space may be written as a linear combination of unit vectors. In a Euclidean space the dot product of two unit vectors is a scalar value amounting to the cosine of the smaller subtended angle.

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Dielectrics in a capacitor #4

Dielectrics in a capacitor increase the potential energy of a capacitor. This happens due to polarization of the dielectric material. The polarized dielectric helps the dielectric to store more charge and therefore increase the electric field value across the capacitor plates. High electric field means more voltage and more voltage across plates increases the stored potential energy. Dielectric material have dielectric strength that determines the factor by which the capacitors energy can be increased. Dielectric constant is a number that is used as a measure of this strength. Higher dielectric strength means more energy storage on capacitor.

00:22 How is a capacitor made? 00:59 How do dielectrics improve capacitor performance? 02:53 What happens when you put a dielectric between capacitor plates? 04:55 What is a dielectric constant? 05:52 Dielectric constants for various materials 06:20 How charge is induced in dielectric 09:27 What is permittivity of a dielectric 10:55 How does polarization of dielectric happen? 12:50 Visual representation - what happens when a dielectric is put between capacitor plates

PDF Summary file: https://the-science-cube.teachable.co... Playlist Capacitors and capacitance: https://youtube.com/playlist?list=PLQ... The Science Cube Subscription: https://the-science-cube.teachable.com/

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Energy stored in a parallel plate capacitor #4

Energy stored in a capacitor is a result of accumulation of charge on the parallel plates of a capacitor. This charge Q builds up due to movement of electrons from one plate to the other. The charge flow is on account of potential difference between the plates due to say a battery with voltage V. So when we charge a capacitor and say the final charge on it is Q and the potential difference is V, we have a formula that connects V and Q through the equation V = Q/C or Q = CV. The energy stored in the capacitor is 1/2 (C V square) 00:33 Energy stored in a capacitor formula derivation 03:59 Formula for potential energy stored in capacitor (capacitor energy storage equation) 04:13 Energy stored in capacitor Vs. energy in compressed spring 06:28 Energy stored between plates of capacitor & energy density of a capacitor

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Capacitors in series and parallel are a combination of capacitors placed in network. In such a network, some capacitors have same voltage across and some same charge. Try to understand the derivation for equivalent capacitance of capacitors in series and in parallel. This will help you use the formula for capacitors in series and parallel a lot more easier.

This lesson has derivation of equivalent capacitance for capacitors in series and parallel. The lesson also has a solved example that finds equivalent capacitance of a network of capacitors.