10th Class Science Magnetic Effects of Electric Current

 Magnetic Effects of Electric Current

• Magnetic field and field lines: The space surrounding a magnet in which magnetic force is exerted is called a magnetic field. The magnetic field lines are the lines drawn in a magnetic field along which a north magnetic pole would move. The magnetic field lines always begin from the N-pole of a magnet and end on the S-pole of the magnet. The strength of magnetic field is indicated by the degree of closeness of the field lines. If the field lines are closer together, the magnetic field is the strongest.

• Magnetic field due to a current carrying conductor: The patterns of various magnetic fields or shapes of field lines produced by a current carrying conductor like straight wire, circular loop and solenoid are given below.

• Magnetic field due to a current through a straight conductor: The magnetic field lines around a straight conductor (straight wire) carrying current are concentric circles whose centres lie on the wire.

• Magnetic field due to a current through a circular loop: The magnitude of magnetic field produced by a current-carrying circular loop (or a circular wire) at its centre is directly proportional to the current passing through the circular loop (or the circular wire), and inversely proportional to the radius of the circular loop (or the circular wire).

• Magnetic field due to a current in a solenoid: The magnetic field produced by a current- carrying solenoid is similar to the magnetic field produced by a bar magnet.

• Force on a current carrying conductor in a magnetic field: A magnet exerts a mechanical force on a current-carrying wire, and if the wire is free to move, this force can produce a motion in the wire.

• Electric motor: An electric motor is a rotating device that converts electrical energy to mechanical energy.

• Electromagnetic induction:

The phenomenon in which an electric current is induced in a circuit because of a changing magnetic field or the motion of the circuit in a magnetic field is called electromagnetic induction. The process of electromagnetic induction has led to the construction of generators for producing electricity at power stations.

• Electric Generator: An electric generator works on the principle that when a straight conductor is moved in a magnetic field, then current is induced in the conductor.

• Direct current and Alternating current: If the current flows in one direction only, it is called direct current. If the current reverses direction after equal intervals of time, it is called alternating current.

• Domestic Electric Circuits: Usually there are two separate circuits in a house, the lighting circuit with a 5 A fuse and the power circuit with a 15 A fuse.

• Earthing of Electrical appliances: We earth the metallic body of an electrical appliance to save ourselves from electric shocks.

• Electric Fuse: A fuse is a safety device having a short length of a thin, tin-plated copper wire having low melting point, which melts and breaks the circuit if the current exceeds a safe value.