15 Things To Know About Magnetic Effect Of Electric Current.

Magnetic Effect of Electric Current Class 10 Notes:-

Magnets:-  Certain rocks behave as a natural magnet. When suspended from a string they align along the south to north direction. These natural magnets contain magnetite (Fe₃0₄ ). Magnets are mainly of two types.

1. Permanent Magnets 
2. Temporary Magnets 

Permanent Magnets   

        The Magnets which retain their magnetism for a long period of time are called permanent magnets(Al, Ni, Co)Aluminium. Nickel and Cobalt is an alloy that is used to make permanent magnets.

Temporary Magnets:- 

         The Magnets which retain their magnetism for a short period of time are called temporary magnets. For example, electromagnets.

Magnets are formed in many shapes such as 

• Bar magnets
• Disc shape Magnet
• Horseshoe Magnet
• Ring Magnets
• Cylindrical Magnets
• Button magnets 

The compass needle is also made up of magnets.

Magnetic Field:-  A Magnet that produces a magnetic field is a space around it that exerts a force on any other magnet placed in it. This is called a magnetic field. 

• All the magnetic field lines are closed curves. They come out of the magnet from the side of the north pole and go into the side of the south pole.
• The field lines are close together near the south pole and spread out away from them.
• The field lines never intersect with each other.

Now questions arise 

Why the field lines never intersect with each other?

                If two filed lines were to intersect then a compass needle placed at the point of intersection would point in two different directions which is not possible.

An electric current produces a magnetic field.

A current-carrying wire produces a magnetic field that can be observed by the magnetic compass.

It will start producing deflection.

Maxwell  Right -Hand Thumb rule:- 

According to Maxwell's right-hand thumb rule, If we imagine keeping a wire in our right in such a way that thumb is in direction current than curved finger s gives us the direction of the magnetic field.

    This is also called as a corkscrew rule.

Diagram 

Magnetic Field Lines due to a current in a single conductor wire:-

In fig current flows from A to B then the magnetic field is in a clockwise direction. In the fig, Current flows from B to A

then the magnetic field is in the anticlockwise direction.

Magnetic  Filed lines due to a current in circular loop:-

In the above diagram, the linear are nearly concentric circles centered on the point. The lines near to the centre of the loop are nearly straight. In fact, the magnetic field at the center of the loop is perpendicular to the plane of the loop.

If the fingers of the right hand are curved along the direction of the current in a loop, the stretched thumb gives the direction of the magnetic field.

Magnetic filed due to solenoid:-

Solenoid  When a long insulated wire is tightly wound in the shape of spring with closely spaced turns that lie side ide, we get a Solenoid.

    The main difference between coil and solenoid is that its length is more than its diameter.

Diagram

By using right-hand thumbs rule we can find out a north pole of the solenoid for e.g. if we stretch our finger along the direction of current than thumb indicates the north pole. Magnetic field lines of a solenoid are similar to that of a bar magnet. But the only difference between strength is there bar magnets have strength at the poles. While solenoid magnetic strength decreases towards the end. The solenoid is also called electromagnet (a material that behaves like a magnet when electricity is passed through it).

Electromagnet:-

         A magnet formed temporarily due to the magnetic field of current is called an electromagnet.

Properties of the Electromagnet:-

• The electromagnet loose its magnetic field when current is switched off.
• Electromagnets are not permanent magnets.
• The poles of electromagnet are not fixed. The poles get interchanged when the direction of the electric current passing through it is changed.

Difference between Electromagnet and permanent Magnets:-

Electromagnet	Permanent magnet
1.   An electromagnet is a temporary  magnet and it can be demagnetized by stopping the current. 2.   Its strength can be changing the current. 3.   The polarity of an electromagnet can be reversed by changing the direction of the current.	1.    A permanent magnet cannot be demagnetized by stopping the current. 2.   Its strength cannot be changing the current and its strength are comparatively weaker than the electromagnets. 3.   The polarity of permanent is fixed.It cannot be reversed by changing the direction of the current.

 

 

 

Fleming Left-hand rule:-

    According to Fleming left-hand rule, if we stretch our fore 

finger and thumb of the left hand at the right angle to each other in such a way that the fore-finger is in the direction of the magnetic field and middle finger is in the direction of the current then thumb g gives us a direction of magnetic force.

diagram

Electromagnetic  Induction:-

The phenomenon in which electric current is induced in a circuit because of changing magnetic field is called electromagnetic induction.

Diagram

Fleming Right-hand rule:-

According to  Fleming right-hand rule, if we stretch our right hand's forefinger, middle finger, and thumb at right angles to each other in such a way that forefinger is in the direction of the magnetic field, the middle finger is in the direction of the current than thumb will give us the direction of the motion.

Diagram

Motor and Generator:-

            A motor is a device that converts electric energy and change it into mechanical energy.

            A generator is a device that uses mechanical energy and changes it into electrical energy.

Electrical energy                 →                Mechanical  Energy

Mechanical Energy             →                Electrical Energy 

Difference between AC and DC

AC	DC
It is called an Alternating current. In AC, there is change in polarity after half cycle. AC current cannot be stored.  Frequency of AC is 50 Hz.	It is called Direct current.   In DC, there is no change in the polarity. DC current can be stored in a battery.   The frequency of  DC is zero.

 Working of the DC Motor :-

DC Motor:-

         A motor is a device that converts electric energy and changes it into mechanical energy.

Principle:- When a current-carrying coil placed inside the magnet having uniform magnetic field, It experiences a magnetic force that is used for the working of the motor.

Construction:-

A magnets are placed within uniform magnetic field and inside the magnet, a soft iron core or shaft is placed between it. There are two brushes B₁ and B₂ which are connected with commutator  C₁ and C₂ and PQ are the wires which are connected with the battery.

Diagram

Working:- The Brush B₁ is connected to the positive terminal of the battery, and B₂ is connected to negative terminal. So, current flows in the coil along ABCD. The figure shows the position of the coil after half a rotation from the initial position. As a result of the rotation, the brushes with which the two halves of the commutator were in contact have got interchanged. This reversed the battery connections to the two arms of the coil has got reversed. Such change takes place for each half-rotation commutator changes the direction of the current in the coil after each half rotation. Using Fleming's left-hand rule, the coil continues to rotate in the anticlockwise direction.

DC Generator:-

     A generator is a device that uses mechanical energy and changes it into electrical energy.

Principle:-

        When a coil is placed inside the magnets having a uniform magnetic field and when this coil moves there is a change in the magnetic field and changing the magnetic field induces a current.

Construction:-

     There is a strong magnet in which shaft is present free eds of the shaft are connected with two halves of the split rings. Two branches B₁ and B₂ are also attached to the commutator C₁ and C₂. There are further joined to the bulb through a wire.

Working:-

    In the figure, brushes B₁ and B2 are in contact with the halves C₁ and C2 commutator B is connected to P and B2 is connected to Q.The arm AB of the coil is moving downwards while the arm DC is moving upwards using fleming left-hand rule, we find that the current &in the coil flows along DCBA. The current flows through the  P to Q.

After half rotation, brushes get interchanged. Now AB is moving upwards and arm DC is moving downwards. This causes the current to flow along ABCD. The current through the bulb remains from P to Q.This  means P always remains at a higher potential than Q.

diagram

Domestic electric circuits:-

Live, neutral and earth wires:-

The live wire is at 220 V.It is red in colour while black is for the neutral and green is for the earth. The current enters an appliance through the live wire and returns through the neutral wire. The appliance is connected across the live and neutral wires. An appliance such as heaters, electric irons have a third terminal called neutral wires.The earth wire does not normally carry current switches that are always connected to the live wires.

5-A and 15-A Wirings:-

 To carry larger current we need thicker wires and better-quality materials in the electrical fittings such as switches and sockets. Two types of electrical fitting are available in the market-one meant for a maximum current of  5A and other for maximum 15A current. The wires used for appliances such as AC refrigerator is 15A wire.

Electrical problems and safety measures:-

Overload:

If the total current drawn through a wire by the appliances connected to it exceeds the safety limit for that wire, it gets overheated. we say overheating is due to overloading.

Short Circuit:- When a very large current passes through the circuit because the resistance between the wires is almost zero. Such an event is called a short circuit.

Safety Devices:-  Safety devices are used in the circuit and are used to breaks the circuit whenever an abnormally high current flows through it. Common safety devices include the fuse and circuit breaker.

 

To be continued ........ some diagrams are left.