wildlifeprotection.info Laws Current Electricity Notes Pdf


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Free PDF download of Class 12 Physics revision notes & short key-notes for Chapter 3 - Current Electricity to score high marks in exams, prepared by expert. The conventional direction of electric current is the direction of motion of positive charge. . Physics Notes for Class 12 chapter 3 CURRENT ELECTRICITY. charges moves to the door. • Door knob is an conductor, the charge flows quickly. The moving charge make a brief intense electric current between you and the.

Current Electricity Notes Pdf

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ONE MARK QUESTIONS WITH ANSWERS. 1. What constitutes an electric current? Ans. Charges in motion constitutes an electric current. 2. Define electric . The free electrons in a metal have three distinct velocities associated with them: ( a) a random velocity (about ms-1). (b) a velocity with which electrical. Physics Current Electricity Notes. 1. Factors Affecting Current. • the natural state of electrons in a wire, or other conductor, is to simply spread out.

Internal resistance of a cell i Increases with increase in concentration of the electrolyte. Relation between E. This law follows law of conservation of charge. Balanced Wheatstone Bridge Wheatstone bridge is also known as a metre bridge or slide wire bridge. This is an arrangement of four resistance in which one resistance is unknown and rest known.

The Wheatstone bridge as shown in figure. The bridge is said to be balanced when deflection in galvanometer is zero, i. It may be remembered that the bridge is most sensitive, when all the four resistances are of the same order. Meter Bridge This is the simplest form of Wheatstone bridge and is specially useful for comparing resistance more accurately. Potentiometer Potentiometer is an ideal device to measure the potential difference between two points.

It consists of a long resistance wire AB of uniform cross section in which a steady direct current is set up by means of a battery.

Exchange Discount Summary

If R be the total resistance of potentiometer wire L its total length, then potential gradient, i. Determination of emf of a Cell using Potentiometer If with a cell of emf E on sliding the contact point we obtain zero deflection in galvanometer G when contact point is at J at a length I from the end where positive terminal of cell have been joined. The figure above shows a wire of length L carrying a current I and lying in a magnetic field of flux density B.

Note that the force is always perpendicular to the plane containing both the current I and the magnetic field B. In each case, a current I of 10 A is directed as shown. Use Fleming's Left Hand Rule to predict the directions of the forces and work out the magnitude of the forces on a 0.

A horizontal uniform magnetic field of direction perpendicular to the axis of the coil passes through the coil. Initially, no mass is placed on the pan and the arm is kept horizontal by adjusting the counter- weight.

When a current of 0. Determine the magnitude of the magnetic flux density and the direction of the current in the coil.

The radius of the path is 0. Given that the mass of the electron is 9.

The electron must be moving clockwise. This is because a ferrous material has a higher permeability than air. Another explanation is that iron, being a ferromagnetic material, becomes magnetised when placed into the solenoid, thus contributing to the overall magnetic field strength of the solenoid.

A large current is momentarily passed through the foil in the direction ABC, and the foil moves. By a similar consideration, the force on AB is also away from BC. Thus the forces between the foils are repulsive. Electromagnetic Induction Electromagnetic induction refers to the phenomenon where an emf is induced when the magnetic flux linking a conductor changes.

Magnetic Flux is defined as the product of the magnetic flux density and the area normal to the field through which the field is passing. It is a scalar quantity and its S. The coil has turns and an area of 25 cm2. And when the switch S is opened, the galvanometer needle moves to the other side momentarily.

At the instant when switch S is either opened or closed, there is a change in magnetic flux in coil A.

The movement in the needle of the galvanometer indicates that when there is a change in magnetic flux in coil A, a current passes through coil B momentarily. This suggests that an EMF is generated in coil B momentarily.


Factors affecting the magnitude of the induced E. When the magnet is not moving, the galvanometer shows no reading. When the magnet is withdrawn from the coil, the galvanometer deflects in the opposite direction momentarily. This generates an induced EMF in the coil that produces an induced current that flows in the coil, causing the deflection in the ammeter.

The magnitude of the deflection depends on the magnetic field density B, the speed of motion v of the magnet, and the number of turns N in the coil.

Chapter 13: Current Electricity Notes for Class 12 [WITH FREE PDF]

Applications of electromagnetic induction Eddy Currents Eddy currents are currents induced in metals moving in a magnetic field or metals that are exposed to a changing magnetic field. Consider a solid metallic cylinder rotating in a B-field as shown: 1.

A force resisting the rotation would be generated as shown. The insulation between the coins increases resistance and reduces eddy current, thus reducing friction or heating.

Applications of Eddy Currents 1. Induction Cooker Changing magnetic fields in the stove generate eddy currents in the base of the metal pot placed on it, thus producing heat.

The element's electronics power a coil that produces a high-frequency electromagnetic field. The field penetrates the metal of the ferrous magnetic-material cooking vessel and sets up a circulating eddy current, which generates heat.

The heat generated in the cooking vessel is transferred to the vessel's contents. Nothing outside the vessel is affected by the field--as soon as the vesse is removed from the element, or the element turned off, heat generation stops.

Note: the process described at 2 above is called an "eddy current"; in fact, most of the heating is from "hysteresis", which means the resistance of the ferrous material to rapid changes in magnetization--but the general idea is the same: the heat is generated in the cookware.

Metal detectors A pulsing current is applied to the coil, which then induces a magnetic field shown. When the magnetic field of the coil moves across metal, such as the coin in this illustration, the field induces electric currents called eddy currents in the coin.

The eddy currents induce their own magnetic field, which generates an opposite current in the coil, which induces a signal indicating the presence of metal.

Electric guitars Electric guitars use electromagnetic pickups in which an induced emf is generated in a coil of wire by a vibrating string. Most guitars have at least two pickup coils located below each string. Each pickup is sensitive to different harmonics produced by the vibrating string.

The string is made from a magnetisable metal, and the pickup consists of a coil of wire within which a permanent magnet is located. The permanent magnet produces a magnetic field that penetrates the guitar string, causing it to become magnetized with north and south poles.

When the string is plucked, it oscillates, thereby changing the magnetic flux that passes through the coil. The changing magnetic flux induces an emf in the coil, and the polarity of this emf alternates with the vibratory motion of the string.

A string vibrating at Hz, for example, induces a hz ac emf in the coil. This signal, after being amplified, is sent to the speakers, which produce a Hz sound wave. Earth-leakage circuit breaker ELCB ELCB is used in electrical circuits in the home to protect the users from electric shocks when there is a fault in the electrical appliance.

The ELCB can be triggered to stop a current, depending on whether an induced voltage appears across a sensing coil.

Current Electricity - Notes and MCQs / Assignments PDF

The sensing coil is wrapped around an iron ring, through which the current carrying wire passes. Under normal operating conditions, the current flowing in the coils A and B are equal but opposite directions.Resend OTP Wanna update details? Chapter 13 - Nuclei.

Job Preparation. RRB Group D. Consider a solid metallic cylinder rotating in a B-field as shown: 1. Determine the EMF of the unknown cell if the balanced point is at B. Voltic, Daniel and Leclanche cells are primary cells.

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