Home Notes MCQ's Qestions NCERT Qestions Worksheets Blogs

Chapter 1:Chemical Reaction And Equations

Chapter 2:Acids, Bases and Salts

Chapter 3:Metals and Non-metals

Chapter 4:Carbon and Its Compounds

Chapter 5: Periodic Classification of Elements

Chapter 6: Life Processes

Chapter 10: Light Reflection and Refraction

Chapter 11:Human Eye and Colourful World

Chapter 12:Electricity

Chapter 13:Magnetic Effects of Electric Current

Chapter 14:Sources of Energy

Chapter 15:Our Environment

Chapter 16:Sustainable Management of Natural Resources

Magnetic Effects of Electric Current class 10 notes Chapter 13

Magnetic effects of electric current mean a current-carrying wire behaves like a magnet

MAGNETIC FIELD:

The The region surrounding a magnet, in which the force of the magnet can be exerted, is called magnetic field
ii)Magnetic field is a vector quantity that has both direction and magnitude

FIELD LINES:
  
The magnetic field lines start from north pole and end at the south pole of magnet
ii)Inside the magnet, the direction of field lines is from its south pole to its north pole

MAGNETIC FIELD DUE TO A CURRENT-CARRYING CONDUCTOR:


When electric current passed in metallic conductor produces a magnetic field around it

Magnetic Field due to a Current through a Straight Conductor:    
The magnetic field produced by a current-carrying straight wire is
i) directly proportional to the current passing in wire
ii)inversely proportional to the distance of the point from the wire

Right-Hand Thumb Rule:
  

Imagine we are holding a current-carrying straight conductor in our right hand such that the thumb points towards the direction of current. Then your fingers will wrap around the conductor in the direction of the field lines of the magnetic field, This is known as the right-hand thumb rule

Magnetic Field due to a Current through a Circular Loop:
  

The right-hand thumb rule can be used for a circular conducting wire . every point of a current-carrying circular loop, the concentric circles representing the magnetic field around. At the centre of circular wire,field lines become straight and perpendicular to the plane of coil.

Magnetic Field due to a Current in a Solenoid:
  

A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.
ii)A strong magnetic field produced inside a solenoid can be used to magnetise a piece of magnetic material, like soft iron, when placed inside the coil .The magnet so formed is called an electromagnet

FORCE ON A CURRENT-CARRYING CONDUCTOR IN A MAGNETIC FIELD:

Andre Marie Ampere’s experiment:


When an current- carring conductor is placed in a magnetic field, it experiences a force. This force is
i) directly proportional to the perpendicular direction of current
ii) directly proportional to the perpendicular to its length and magnetic field.

Fleming’s left-hand rule:

stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular If the first finger in the direction of magnetic field and the second finger in the direction of current, and the thumb will point in the force acting on the conductor


ELECTRIC MOTOR:
An electric motor is a rotating device that converts electrical energy to mechanical energy.

Principle:
when a rectangular coil is placed in a magnetic field and current is passed through it, a force acts on the coil which rotates it continuously.

Construction:


An electric motor, consists of a rectangular coil ABCD of insulated copper wire. The coil is placed between the two poles of a magnetic field such that the arm AB and CD are perpendicular to the direction of the magnetic field. The ends of the coil are connected to the two halves P and Q of a split ring. The inner sides of these halves are insulated and attached to an axle. The external conducting edges of P and Q touch two conducting stationary brushes X and Y, respectively,

Working: Current in the coil ABCD enters from the source battery through conducting brush X and flows back to the battery through brush Y. the current in arm AB of the coil flows from A to B. In arm CD it flows from C to D, that is, opposite to the direction of current through arm AB. On applying Fleming’s left hand rule for the direction of force on a current-carrying conductor in a magnetic field the force acting on arm AB pushes it downwards while the force acting on arm CD pushes it upwards and it rotate anti-clockwise. At half rotation, Q makes contact with the brush X and P with brush Y. the current in the coil gets reversed and flows along the path DCBA. The reversal of current also reverses the direction of force acting on the two arms AB and CD. so it pushed down. Therefore the coil and the axle rotate half a turn more in the same direction. The reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil and to the axle

Power Source: A simple motor usually has a DC power source. It supplies power to the motor armature or field coils.
Commutator: A device that reverses the direction of flow of current through a circuit is called a commutator.
Field Magnet The magnetic field helps to produce a torque on the rotating armature coil by virtue of Fleming’s left-hand rule.

Brushes:: It is a device that conducts current between stationary wires and moving parts, most commonly the rotating shaft

The commercial motors use:(i) an electromagnet in place of permanent magnet;
(ii) large number of turns of the conducting wire in the currentcarrying coil;
(iii) a soft iron core on which the coil is wound.

ELECTROMAGNETIC INDUCTION:

Faraday’s experiment:
     

Faraday discovered that a magnetic field communicat with an electric circuit by inducing a voltage known a electromotive force by electromagnetic induction.
When a strong bar magnet is moved toward the coil the galvanometer show deflection

Electromagnetic induction:The phenomenon of production induced EMF due to change in magnetic field with close circuit

Fleming’s right-hand rule:



If we stretch the thumb, forefinger and middle finger of the right hand mutually perpendicular to each other and If the thumb indicates the direction of the movement of conductor, fore-finger indicating direction of the magnetic field, then the middle finger indicates direction of the induced curren

ELECTRIC GENERATOR:
A generator converts mechanical energy into electrical energy




Principle:It is base on principle of electromagnetic induction such that when a straight conductor is moved in a magnetic field then currentis induced in conductor

Constuction: An electric generator consists of a rotating rectangular coil ABCD placed between the two poles of a permanent magnet. The two ends of this coil are connected to the two rings R1 and R2. The inner side of these rings are made insulated. The two conducting stationary brushes B1 and B2 are kept pressed separately on the rings R1 and R2, respectively. The two rings R1 and R2 are internally attached to an axle. The axle may be mechanically rotated from outside to rotate the coil inside the magnetic field. Outer ends of the two brushes are connected to the galvanometer to show the flow of current in the given external circuit.

Working: The rotating the loop in a magnetic field, the side AB moves upward and the side CD moves downwards respectively in the produced magnetic field. Thus, current is induced in it whose direction can be determined by Flemings right hand rule. After half rotation, the ring P comes in contact with brush Y and the ring Q, comes in contact with brush X. Thus, the brush X is always in contact with the side moving upwards and brush Y is always in contact with side moving downwards as a result of which the current flows in one direction. This current is called direct current. This type of generator is called D.C. generator. Similarly, instead of a half ring, if a full ring is used then, A.C. current can be generated and such a generator is called an A.C. generator.

Note: The difference between the direct and alternating currents is that the direct current always flows in one direction, whereas the alternating current reverses its direction periodically.

DOMESTIC ELECTRIC CIRCUITS:




i)AC electric power of 220 V receive in our house with a frequency of 50 Hz.
ii)Earth wire has a voltage of 0V and is covered with green insulation

Electric Fuse

i) Overloading can occur when the live wire and the neutral wire come into direct contact. This occurs when the insulation of wires is damaged or there is a fault in the appliance
ii)The use of an electric fuse prevents the electric circuit and the appliance from a possible damage by stopping the flow of unduly high electric current
iii) overloading the current in circuit increases and becomes hazardous. Joule’s heating in the fuse device melts the circuit and breaks the flow of current in the circuit
iv)Fuse work as protective device in an electrical circuit in times of overloading. when we too many appliances of high power rating are used at the same time