In this post, we will solve numerical questions or problems related to the emf of a cell and internal resistance. We will also use the concepts of terminal potential difference, Open circuit, short circuit, & closed circuit, V-I curve, etc. to solve the problems using equations like V = E – Ir. emf and internal […]

# Current Electricity_21

## Seebeck effect

In this post, we will discuss the Seebeck effect or thermoelectric effect and other related points like thermocouple, thermoelectric emf, thermoelectric series, variation in thermoelectric emf with temperature, Neutral and Inversion temperature, etc. Seebeck effect or thermoelectric effect In 1821, German Physicist Thomas Johann Seebeck discovered that in a circuit consisting of two dissimilar metals […]

## Applications of the heating effect of current | applications of Joule heating

In this post, we will discuss some applications of the heating effect of current (applications of Joule heating). Applications of the heating effect of current Here are some examples of applications of Joule heating (Applications of the heating effect of current). (i) Electric heating device Electric iron, electric heater, and electric toaster are some of […]

## Heating effect of electric current Joule’s law

In a conductor, due to thermal agitation, the free electrons are always at random motion making collisions with ions or atoms of the conductor. When a voltage V is applied between the ends of the conductor, resulting in the flow of current I, the free electrons are accelerated. Hence the electrons gain energy at the […]

## Temperature coefficient of resistance – formula

The temperature dependence of resistance of a conductor can be expressed with the formula R2 = R1 ( 1 + α t), where α is the temperature coefficient of resistance of the conductor. R2 and R1 represent the resistance of the conductor at t2° centigrade and t1° centigrade respectively. In the equation, t = temperature […]

## Temperature dependence of resistivity

The variation of resistivity of a metallic conductor, an alloy, a semiconductor, or an insulator with an increase in temperature is not the same in all cases. Temperature dependence of resistivity of a metallic conductor In terms of relaxation time, the resistivity of the material of a metallic conductor is given by: ρ = (m)/(ne2τ) […]

## j = sigma e derivation for the Vector form of Ohm’s law

In this post, we will derive the equation j = sigma e and we will do the derivation using Ohm’s law equation (V=IR). Obtaining this equation vec J = σ vec E, or deriving J = σ E helps us to get the relationship between the current density, conductivity, and electric field intensity. This J = […]

## Dimension of Resistance | electric Resistance dimension

Resistance R of the conductor is the ratio of the potential difference to the current. R =V/I. Now, let’s find out the dimension of resistance. (Dimensional formula) Dimension of resistance Using equations or formulas, we are going to find out the dimension of resistance. (dimensional formula) R = V/I = [W/Q]/I =[(F s) / (I […]

## Resistivity or specific resistance (ρ)

Resistivity or specific resistance – While deriving Ohm’s Law with the help of drift velocity equations, we got the expression or formula of resistance as follows: R = [(mL)/(ne2τA)]. Here, m = mass of an electron, L = length of the conducting wire, n = electron density or number of electrons per unit volume, e […]

## Derivation of Ohm’s Law class 12 (using drift velocity equations)

Derivation of Ohm’s Law class 12 – Here, in this post, we will derive Ohm’s Law using drift velocity equations following the class 12 syllabus. Know more about the fundamentals of Ohm’s law, graph, etc. here. Derivation of Ohm’s Law class 12 Here, we will take the help of 2 equations or formulas of drift […]

## Drift velocity and mobility of an electron

In this post, we will see how the drift velocity of an electron is related to its mobility. The drift velocity of an electron can be expressed as vd = ( Ee/m) τ, where vd is the drift velocity, E is the electric field, e is the charge of an electron, and m is the […]

## Drift velocity formula derivation

Drift velocity formula derivation – In this post, we will first understand the concept and definition of the drift velocity of an electron and then we will derive the drift velocity formula.

## Drift velocity formula

In this post, we will present the drift velocity formula or equation in terms of different variables like the mobility of an electron, electric current, current density, relaxation time, electric field, potential difference or voltage, and the length of the wire. Drift velocity formula in terms of mobility When electric field E = 1 Vm-1, […]

## Electric current & shock

This post is a compilation of a set questions with answers related to electric current flow and electric shock. What levels of current are dangerous? Approximately 1 mA (0.001 A) is enough to produce a tingling sensation. 10 mA is painful. 12-20 mA is enough to paralyze muscles, making it impossible to let go. 60-100 […]

## How to use the PIV Triangle for the Electrical Power formula

The power formula expresses fundamental relationships among power, current, and voltage. On occasion, you may be asked to calculate any one of the three variables in this equation, given the other two. As a result, good mnemonics to remember is the PIV triangle. PIV triangle for the Electrical Power formula (Diagram) How to use the […]

## How to use the VIR Triangle for Ohm’s Law?

Ohm’s Law expresses fundamental relationships among voltage, current, and resistance. On occasion, you may be asked to calculate any one of the three variables in this equation, given the other two. As a result, good mnemonics to remember is the VIR triangle. VIR triangle for Ohm’s Law (Diagram) How to use the VIR Triangle for […]

## Resistance of metal increases with an increase in temperature – how?

When current flows through the material of a circuit, such as the metal of the connecting wires, the material of the circuit gets in the way of the flow of the charge. On a microscopic level, as the electrons flow through the metal they collide with the vibrating positive ion cores of the metal structure. […]

## AQA GCSE Physics – Equations & Formulae from Electricity chapter

The image below shows a list of equations and formulae from the chapter “Electricity” of the GCSE Physics syllabus. This is also helpful for all other equivalent boards like CBSE, ISC, ICSE. Equations to learn from Electricity chapter of physics syllabus

## Resistivity and Conductivity Solved numerical problems (Worked Solutions)

In this post, we have compiled a bunch of interesting numerical problems on Resistivity and Conductivity. These are Solved numerical problems (Worked Solutions). Resistivity and Conductivity numerical problems (solved worksheet) 1 ) Gold has a conductivity of 45 MS m−1. What is the resistance of a 0.01 m diameter gold connector that is 0.05m long? […]

## Kirchhoff’s Voltage law, KVL – statement, formula, example, sign convention

in any electrical circuit, the energy being converted into electrical energy (in the sources of emf) must be equal to the energy being transferred from electrical to internal, by the sinks of Potential Difference. This is Kirchhoff’s second law equivalent to conservation of energy.

ref: IB physics course book by David Homer MB-J

## Heating effect of electric current class 10 – formulas & Numerical

In this post, we will discuss the Heating effect of electric current (class 10) and list down the Heating Effect formulas or Equations of electric power and energy. And, then we will solve a bunch of numerical problems as well using these formulas. Heating effect of current formulas for power and energy The power P […]

## Measuring the resistance of a component – different ways

In this post, we are going to discuss different ways of measuring the resistance of a component. Resistance is defined as R = V/I. This obviously gives ways of measuring resistance, as in the circuits shown below. Each of the first 2 methods listed below uses both an ammeter and a voltmeter. And, the third […]

## Numerical problems on Resistivity with solution

This post presents a few important numerical problems in physics that you can solve using the concepts of resistivity. If you want a quick revision to memorize the resistivity formula then you can check this post on resistivity formula derivation. Note: Remember that: (1) resistivity is a property of the material (2) the unit of […]

## AC Waveforms of different types

Alternating Current,(AC) is a current that changes direction cyclically, passing first in one direction, then in the other through a circuit. Such alternating currents are produced by generators and other such voltage sources whose polarities alternate between a positive direction and a negative direction rather than being fixed in a constant direction as with DC […]

## Conductors & Insulators with examples & How do they differ?

In some materials, electrons move easily from atom to atom. In others, the electrons move with difficulty. And in some materials, it is almost impossible to get them to move. In this post, we will briefly talk about Conductors & Insulators to find out how they differ. Conductors An electrical conductor is a substance in […]

## Conservation of Charge & Energy in electrical Circuits

In this post, we will have some pointers on the Conservation of Charge & Energy in electrical Circuits. Charge Doesn’t ‘Leak Away’ Anywhere — it’s Conserved in electrical circuits. Energy is Conserved too. Charge Doesn’t ‘Leak Away’ Anywhere — it’s Conserved in electrical Circuits 1) As charge flows through a circuit, it doesn’t get used […]

## Ammeters and Voltmeters

Ammeters measure the current of a circuit, and voltmeters measure the voltage drop across a resistor. Ammeters and voltmeters are cleverly designed because it is important in the design to make sure that the use of these meters doesn’t change the circuit in such a way as to influence the readings. While both types of […]

## Kirchhoff’s first law | Kirchhoff’s Current Law (KCL) – Explained & derived

Gustav Kirchhoff, an eminent German physicist is the person behind Kirchhoff’s first law dealing with electric current. This law is also known as Kirchhoff’s Current Law or KCL. The KCL states that, for any point or node in an electrical circuit, the sum of currents into that point is equal to the sum of currents […]

## Numerical problems on Drift velocity of electrons and electric current-how to solve?

The numerical problems in this post are based on the drift velocity of electrons and electric current. Electric Current is expressed as I = nAve ( see the derivation of electric current and drift velocity equation ) Numerical problems on Drift velocity of electrons and electric current 1 ] A copper wire has a cross […]

## What is the Internal Resistance of cells?

What is the Internal Resistance of cells & how it affects the current flow in a circuit? All electric cells are made of materials that have resistance. The resistance of the cell is called the internal resistance. If a cell with internal resistance is connected to a resistor, the current will flow from the cell. […]

## How Small drift speed of electron causes high-speed electric current?

Most charge carriers, like electrons, move slowly. how the Small drift speed of electrons causes a high-speed electric current?

## How to Derive the relationship between Current and drift velocity

So this is the equation describing the relationship between current(I) and the drift velocity(v). Derivation of drift velocity equation

## The resistivity of different materials – shown in a table

Resistivity values of silver, copper, aluminium, constantan, germanium, silicon, polyethene, and glass are listed in the above table.

## Symbols & functions of Common components of electrical circuits – How to get?

Figure 1 below presents 17 circuit symbols for a variety of circuit components like cell, battery, switch open, switch closed, ammeter, voltmeter, motor, resistor, thermistor, fuse, diode, LED (Light Emitting Diode), LDR (Light Dependent Resistor), Filament lamp, variable resistor, d.c. supply, & a.c. supply. Symbols & functions of Common components The following tables describe some […]

## Voltages in series circuits and parallel circuits – easy understanding

Voltages in series circuits and parallel circuits – Let’s see how total voltage in series circuits and parallel circuits are calculated. Voltages in series circuits A series circuit has no junction. Now if there is any group of EMFs that follow in series in such junctionless circuit then the total voltage or emf of the […]

## How current flows through series and parallel circuits? A quick reference

Here we will see how current flows through series and parallel circuits. Currents in series circuits In a series circuit, devices are connected so there is only one closed path for current to follow. However, if any part of this path is broken, current will no longer flow in the circuit. Any group of components […]

## Relation between resistance and resistivity through a simple experiment

In this post, we will cover How to find the Relation between resistance and resistivity through a simple experiment. It’s basically deriving the resistivity formula with our understanding of electrical resistance. Once we derive the equation or formula of resistance, the definition, symbol, and formula of resistivity will be prominent to us. To do this […]

## How to identify I-V graph of a Thermistor & I-V graph of a filament bulb?

How to identify the I-V graph of a Thermistor and the I-V graph of a filament bulb? Here we will discuss how to do that.

## Equivalent resistance of a parallel circuit with derivation & numerical problems

The equivalent resistance of a parallel circuit is found using Kirchoff’s junction rule, which states that the sum of the currents entering a branch (or junction) must be equal to the sum of the currents leaving a branch (or junction). This is illustrated in Figure 1 (the black dot represents the branch point). See how […]

## Series Circuits, Resistors in series & equivalent resistance – numerical

What is a series circuit? A series circuit consists of several resistors connected in sequence, one after the other. This increases the length of the conductor. Therefore total resistance increases as the number of resistors in series are increased in the circuit. Characteristics of Series Circuit as found from experiments Experiments show that the current […]