Question

Answer the following questions:-
a) State the principal of electric motor.
b) What is the function of a split ring commutator?
c) What is the disadvantage of using a thick fuse wire?

Include all the important key words in these questions.

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Answer 1

Solution:-

=> i) Electric motor work on the principal that when ever a current carrying conductor place in magnetic field which experience some force . Due to which its start Rotating

=> ii) Split ring or commutator it help to change the direction of current after every half rotation due to which its rotates in same direction and split rings which connected with terminal of battery

=> iii) Disadvantages of using thick fuse wire

We know that

Resistivity Formula

=> R = ρl/A

So resistivity is inversely proportional to area of cross section

So if thick wire is use in fuse when heavy currents pass through fuse it is easily passed through fuse because of thick wire due to which it is high chance of short circuit

More information about melting of fuse wire

When current flow through fuse wire it get heated up till its melting point at its melting point equilibrium is achieved

At equilibrium

Heat produce by current per unit time = Heat radiated by wire per unit time from surface

Answer 2

Answer:

• The principle of an electric motor is based on the current carrying conductor which produces magnetic field around it. A current carrying conductor is placed perpendicular to the magnetic field so that it experiences a force. It converts electrical energy into kinetic energy (mechanical energy) through the interaction of the two magnetic fields.

• The split ring has the function of reversing the current at that point. When a dc motor shaft comes into contact with a split ring, the split ring reverses the current to maintain the shaft torque in a magnetic field.Split ring is used for reversing the direction of current in the coil.

• Disadvantage: During short circuit or overload once fuse blows off replacing of fuse takes time. During this period the circuit lost power. When fuses are connected in series it is difficult to discriminate the fuse unless the fuse has significant size difference.

The resistance of a conductor is proportional to its length and inverse proportional to its cross-sectional area. So, If the fuse wires are thick, the larger cross section decreases the resistance across the fuse wire.

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Magnet: Magnetic field and magnetic field lines, Magnetic field due to a current carrying conductor, Right hand thumb rule, Magnetic field due to current through a circular loop. Magnetic field due to current in a solenoid.

Magnet is an object that attracts objects made of iron, cobalt and nickle. Magnet comes to rest in North – South direction, when suspended freely.

Use of Magnets: Magnets are used

• in refrigerators.
• in radio and stereo speakers.
• in audio and video cassette players.
• in children’s toys and;
• on hard discs and floppies of computers.

Properties of Magnet

A free suspended magnet always points towards the north and south direction.

The pole of a magnet which points toward north direction is called north pole or north-seeking.

The pole of a magnet which points toward south direction is called south pole or south seeking.

Like poles of magnets repel each other while unlike poles of magnets attract each other.