Physics
Magnetic Effects of Current
Chapter-12
Question/Answer:
1. What is the magnetic effect of current flow?
Ans: If current flows through a conductor, a magnetic field is created around it. This is known as the magnetic effect of current flow.
2. What is the fundamental principle of electrical motor?
Ans: Effects of the magnet on the current flowing wire.
3. What is an electric motor?
Ans: An electrical motor is a machine, that converts electrical energy into mechanical energy.
4. How to increase the intensity of an electromagnet?
Ans: By increasing current flow, increasing the number of turns in the solenoid, by bending the solenoid like 'U' letter, the intensity of an electromagnet can be increased.
5. What is induced current flow?
Ans: By changing the distance of a movable magnet or current flowing circuit or by changing the current flow, the temporary flow that is created on the closed circuit, is known as induced current flow.
6. What is electromagnetic induction?
Ans: With the help of an external changing magnetic field, the incident of creating electromotive force or current flow in a closed circuit is known as electromagnetic induction.
7. What is solenoid?
Ans: Solenoid is a coil of wire through which if the current is flown a strong magnetic field is created on the coil of wire.
8. Which machine is based on electromagnetic induction?
Ans: Generator is based on electromagnetic induction.
9. How can the intensity of electromagnet be increased?
Ans: Ways for raising the intensity of an electromagnet:
a) raising the flow of current.
b) raising the number of turns on the solenoid.
c) bending the iron bar into the shape of the alphabet U and keeping both the ends of U as close as possible.
10. What is an electromagnet?
Ans: If a piece of soft iron is placed down the centre of a solenoid, the strength of the magnetic field increases. This combination of solenoid and soft iron core is called an electromagnet.
An electromagnet attracts magnetic objects when it is switched on.
11. If you send an electron beam from one end to the other end of your room and see that it is going upward, what explanation will you give?
Ans: You want to send beams of electrons from one corner to other corners of your room. You have seen that it is going upward. Explain the reason.
Earth is a huge magnet. We know that geomagnet's north pole is closer to magnet's south pole and geomagnet's south pole is closer to the magnet's north pole.
The horizontal component of earth's magnetic field acts from north to south. If we want to send beams of electrons from one corner to another we may observe:
a) Electron beam is passed from east to west
b) If the beam of electrons goes upward then the room may be at the equator region.
12. While making an electromagnet, an insulated wire is wrapped around an iron bar. Is it better to use a single turn with a thick wire or many turns with a thin wire? Why?
Ans: It is better to wrap an iron bar with an insulated wire to make an electroma net. We know the more is the flow of electrons through the wire, the more are the magnetic field.
If we want to make a strong magnetic field, many turns of wire is done rather than a single circular loop. This is called solenoid. A strong magnetic field can be made by solenoid.
So, a strong magnetic field can be produced if every loop conducts electricity and the magnetic field will be many times greater.
13. What is the magnetic effect of electric current?
Ans: Magnetic effect of electric current refers to the phenomenon of transient current flow in a circuit without any electric device in case an iron bar is placed very close to a wire conducting electric current.
14. What is the difference between a generator and an electric motor?
Ans: A generator is a power-generating device with which mechanical energy is converted to electrical energy.
The making of a generator is based on the principle of electromagnetic induction.
Most of the electricity we use in our homes is produced by generators. Inside a generator, coils of wire are rotated
between the poles of a magnet. As the coils rotate, they cut through magnetic field lines generating current.
An electric motor is a device with which electrical energy is converted to kinetic energy.
This device is founded on the principle of magnetic effect on wires conducting electric current.
Motors are of multipurpose use in comparison to generators.
In case of motors, the single loop of wire is replaced with a coil of wire with many turns and
the permanent magnet is often replaced with an electromagnet.
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