Current Electricity_21

emf and internal resistance questions – numerical

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 […]

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 […]

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 […]

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

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 […]

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? […]

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 […]

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. […]

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 […]

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 […]

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 […]

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