Magnetic Field and Field Lines
Iron fillings near the bar magnet align themselves along the field lines. Magnet exerts a force on the iron fillings that make them get arranged in such a pattern. The magnetic field is the region around the magnet where such power is experienced. The lines along which iron fillings get aligned due to the magnet’s force are called magnetic field lines.
The magnetic field is a quantity that has both direction and magnitude. Field lines emerge from the north pole and merge at the south pole. The direction of these lines inside the magnet is from the south pole to the north pole. No two lines cross each other. This is because, if they did cross, then the compass needle would point in two directions at the point of intersection, which is impossible. Let us now learn in detail about class 10 magnetic effects of electric current notes.
Magnetic Field Due to Current Carrying Straight Conductor
The magnetic field is produced around a current-carrying conductor. The magnitude of the magnetic field increases as we pass more current through the wire or conductor. The magnitude of the magnetic field decreases as we increase the distance from the current-carrying wire, even though the current through the wire is the same.
Right-Hand Thumb Rule
This rule finds the direction in which a current-carrying conductor generates the magnetic field. As per this rule, you must imagine yourself holding the current-carrying conductor in your right hand, and your right thumb should be pointing in the way the current is passing. Then, the way in which your fingers wrap around the conductor is the direction of the field lines of the magnetic field.
Magnetic Field Due to Current Through a Circular Loop
The magnetic field produced by a current-carrying straight conductor is inversely proportional to the distance from the conductor. The concentric circles representing the magnetic field become larger and larger as we move away from the wire in the case of a circular loop. As we reach the centre of the loop, the magnetic field lines appear to be almost straight.
The magnetic field of a current-carrying wire shall depend on the current passing through it. Hence, in a circular coil with n turns, the magnetic field shall be n times as large as that produced by a single turn.
Magnetic Field Due to Current in a Solenoid
A coil with many circular turns of insulated wire which is closely wrapped in the shape of a cylinder is called a solenoid. The magnetic field pattern of a current-carrying solenoid is like that of a bar magnet. One end of the solenoid acts as the north pole, and the other end as the south pole. But the field lines inside the solenoid are in the form of parallel straight lines. Hence, the magnetic field is the same at all the points of the solenoid. A magnetic material can be magnetised using the solenoid structure. Since you now have an idea about magnetism class 10, let us learn about its various applications.
Force of a Current Carrying Conductor
The magnetic field of a current-carrying conductor exerts a force on the magnet placed in its vicinity, and the magnet also exerts an equal and opposite force on the current-carrying conductor. The direction of force gets reversed when the direction of current through the conductor gets reversed. The direction of the force depends on the direction of the current and the direction of the magnetic field. By using Fleming’s left-hand thumb rule, If the first finger is pointing in the direction of the magnetic field and the second finger is pointing in the direction of the current, then the third finger shall point in the direction of force acting on the current carrying conductor.
As part of class 10 science chapter 13 notes, we shall now learn about the electric motor concept. Electric motors used in fans, mixers, refrigerators, computers, etc., are rotating devices that convert electrical energy into mechanical energy. Electric motors consist of commutators that reverse the direction of the flow of current through the circuit. The reversing of current on a repetitive basis ensures that there is continuous rotation.
A rectangular coil of insulated copper wire, let’s say ABCD, comprises an electric motor. The coil is positioned so that the arm AB and CD are perpendicular to the magnetic field’s direction, which lies between its two poles. The coil’s ends are attached to the split ring’s P and Q halves. These halves’ inside sides are insulated and connected to an axle. As seen in the image, the external conducting edges of P and Q make contact with X and Y, two stationary conducting brushes.
Through conducting brush X, current enters the coil ABCD from the source battery and exits through brush Y to return to the battery. Keep in mind that the coil’s arm AB has a current flowing from A to B. In arm CD, the current runs in the opposite direction as arm AB, from C to D. Regarding using Fleming’s left-hand rule to determine the force’s direction on a conductor that is carrying current in a magnetic field.
We discover that the force pushing arm AB forces it to go downward, whereas the force pushing arm CD moves it upward. As a result, the coil and axle O, which are placed freely to spin around an axis, rotate counterclockwise. Q makes contact with brush X at half rotation, whereas P makes contact with brush Y. As a result, the current in the coil reverses direction and travels along the DCBA. A commutator is a component that changes the direction in which current flows across a circuit. The split ring serves as the commutator in electric motors. The direction of the force exerted on the two arms; the current reversal also reverses AB and CD.
As a result, the coil’s arm AB, which had previously been forced down, is now pushed up, while the arm CD, which had previously been pushed up, is now pulled down. As a result, the coil and axle bend inward by half a turn.
At each half cycle, the current is reversed, causing the coil and axle to continue to rotate.
Commercial motors use an electromagnet for a permanent magnet, a coil that carries electricity, a lot of conducting wire turns, and a soft iron core around which the coil is twisted. The
An armature is made up of the coils themselves, a soft iron core, and the coils. This increases the power of the motor.
English physicist Michael Faraday is the one who first studied electromagnetic induction. He discovered that by moving a magnet, he could produce electric currents. The motion of the magnet in relation to the current-carrying coil produces a potential difference that is induced and which results in an electric current in the circuit.
The process of changing the magnetic field of a conductor that results in a current being induced in another conductor is called as electromagnetic induction. Current can be induced in a coil in two ways. One is by moving it in a magnetic field, and the other method is by changing the magnetic field around it. The induced current is the highest when the direction of motion of the conductor is at right angles to the magnetic field. Fleming’s right-hand rule can be used to find out in which direction is the induced current flowing.
We have seen and learned about electromagnetic induction as part of ch 13 science class 10 notes. The induced current in this phenomenon is very small. The electric generator uses the same phenomenon to generate large amounts of induced currents that can be used in homes and industries. The electric generator uses mechanical energy to rotate a conductor present in a magnetic field to generate electricity.
A current that changes its direction after equal time intervals is called an alternating current. Alternating current is abbreviated as AC. An electric generator that works on AC is called an AC generator. A current that does not change its direction with time is called a direct current, and it is abbreviated as DC. A split-ring commutator is used in generators to obtain DC. Electric generators that use unidirectional current or DC is called DC generator. Power stations in India depend on AC for the generation of power or electricity. In India, AC has a frequency of 50Hz. An advantage of AC over DC is that AC allows electric power to be transmitted over long distances without loss of energy.
As seen in the figure, an electric generator is made up of a revolving rectangular coil ABCD positioned in the middle of a permanent magnet’s poles. The two rings, R1 and R2, are attached to this coil’s two ends. These rings have an insulated inner side. Keep the two stationary conducting brushes B1 and B2, pushed on the rings R1 and R2, respectively. An internal connection is made between two rings, R1 and R2, with an axle. The coil inside the magnetic field can be rotated mechanically by turning the axle from the outside.
To display the current flow in the specified external circuit, the galvanometer is attached to the two brushes’ outer ends.
When the axle that is connected to the two rings is turned, the magnetic field created by the permanent magnet causes arm AB to travel upward (and arm CD to move downward). Let’s assume that the setup in the given figure rotates the coil ABCD in a clockwise direction. The induced currents are built up in these arms along the directions AB and CD by using Fleming’s right-hand rule. As a result, an induced current moves in the ABCD direction. The current created in each turn of a coil with more turns add up to a significant current flowing through the coil. As a result, B2 to B1 are where the external circuit’s current flows.
Arms CD and AB begin to rotate in opposite directions after half a rotation. As a result, the induced currents in both arms change in direction, resulting in the net-induced current flowing in the direction of DCBA. Now, B1 to B2 is the flow of current in the external circuit. Hence the direction of the current in each arm changes every half rotation. A current like that, which reverses direction at regular intervals, is referred to as an alternating current (abbreviated as AC). This device is also known as an AC generator.
A split-ring type commutator must be employed to produce a direct current (DC), which does not change its direction over time. With this configuration, one brush is constantly in contact with the arm that is travelling up the field, while the other brush is constantly in contact with the arm that is travelling down. A split ring commutator’s operation has been demonstrated in the context of an electric motor. As a result, a unidirectional current is generated. Thus, the generator is referred to as a DC generator.
Domestic Electric Circuits
The electricity we receive in our homes flows through the main supply. The main supply is obtained from poles or through underground cables. There are two types of wires involved. The red wire is called the live wire or positive, and the black one is called the neutral wire or negative. The potential difference between the two in India is two hundred twenty volts. There is also a green insulated wire called the earth wire, which is usually connected to a metal plate deep into the earth near the house. This wire is used for the safety of humans, and it ensures that the user of various appliances does not suffer from electric shocks.
Electricity comes into the house from the mains through the fuse in the meter board. The electricity flows into the line wires of the house through the main switch. The electricity is supplied to various circuits within our homes.