Tag: magnetic effects of electric current

Questions Related to magnetic effects of electric current

The magnetic lines of force due to straight current carrying conductor are:

physics magnetic effects of electric current magnetic field due to a circular current carrying conductor magnetic field produced in a circular loop oersted experiment field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

  1. circular lines

  2. straight lines

  3. concentric lines

  4. elliptical lines

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Correct Option: A

What is the shape of a current-carrying conductor whose magnetic field pattern resembles that of a bar magnet?

physics magnetic effects of electric current magnetic field due to a circular current carrying conductor magnetic field produced in a circular loop oersted experiment

  1. circular loop

  2. straight

  3. U-shaped

  4. solenoid

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Correct Option: D
Explanation:

Answer is D.

A solenoid is an electromagnet. That is, it acts as a bar magnet only when electricity is passed through it. Its purpose is to generate a controlled magnetic field. 
A solenoid is a coil of insulated or enameled wire wound on a rod shaped form made of solid iron solid steel or powdered iron.

The working of a generator is based upon the

physics effects of electric current electric generator ac generator magnetic effects of electric current

  1. magnetic effect of current

  2. heating effect of current

  3. chemical effect of current

  4. electromagnetic induction

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Correct Option: D
Explanation:

The working of a generator in based on the phenomenon of electromagnetic induction.

Suggest way/s in an a.c. generator to produce a higher e.m.f.

physics magnetic effects of electric current electric generator ac generator effects of electric current

  1. By increasing the speed of rotation of coil

  2. By increasing the number of turns in the coil

  3. both A & B

  4. None of the above

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Correct Option: C
Explanation:
C. both A & B.
In an a.c. generator to produce a higher emf-
1. By increasing the speed of rotation of the coil.
2. By increasing the number of turns in the coil.

The laws of electromagnetic induction have been used in the construction of a :

physics magnetic effects of electric current electric generator ac generator effects of electric current

  1. galvanometer

  2. voltmeter

  3. electric motor

  4. electric generator

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Correct Option: D
Explanation:

The laws of electromagnetic induction has been used in the construction of a electric generator. In electric generator, emf is induced by changing the flux.
Galvanometer is used to detect current. So, no use of electromagnetic induction.
Voltmeter is used to measure voltage. Again, no use of electromagnetic induction.
Electric motor changes electrical energy into mechanical energy, which has no use of laws of electromagnetic induction.

A D.C. generator is based on the principle of.

physics magnetic effects of electric current electric generator ac generator effects of electric current

  1. magnetic effect ofcurrent

  2. lighting effect ofcurrent

  3. electrochemical induction

  4. electromagnetic induction

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Correct Option: D
Explanation:

Answer is D.

Electromagnetic induction is a process where a conductor placed in a changing magnetic field (or a conductor moving through a stationary magnetic field) causes the production of a voltage across the conductor. This process of electromagnetic induction, in turn, causes an electrical current - it is said to induce the current.
Hence, the D.C. generator is based on the principle of electromagnetic induction.

In an electric generator ,split rings are used for 

physics effects of electric current electric generator ac generator magnetic effects of electric current

  1. Converting DC to AC

  2. Converting AC to DC

  3. Reducing power consumption

  4. To split the current

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Correct Option: B
Explanation:

Answer is B.

The electric generator is devised to convert mechanical power into electrical power. Permanent magnet (PM) current converts into electrical energy through the interaction of two magnetic fields. One field is produced by a permanent magnet assembly, the other field is produced by an electrical current flowing in the rectangular coil ABCD, through the brushes and split-ring commutators. These two fields result in a torque which tends to rotate the coil. As the coil turns, the current in the winding is commutated to produce a continuous torque output. 
The split ring commutator is made from 2 pieces of copper that are held apart in the center from touching each other. They look like a copper ring split in the middle. The effect of using split rings in a electric generator is that the direction of the current flowing in the coil is reversed and DC current is generated.

If the speed of rotation of armature coil is increased in an AC generator

physics effects of electric current electric generator ac generator magnetic effects of electric current

  1. Magnitude of current increases

  2. Frequency of current increases

  3. Both 1 and 2

  4. Magnitude of current increases, frequency decreases

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Correct Option: C
Explanation:

If the speed of rotation of armature coil is increased in an AC generator

$\mathscr{E} = NAB\omega  \sin \theta$,Magnitude of current increases,Frequency of current increases The option C is correct.

A feature common to both AC and DC generator is ______.

physics effects of electric current electric generator ac generator magnetic effects of electric current

  1. Split rings

  2. Electrical energy is converted to mechanical energy

  3. Slip rings

  4. Mechanical energy is converted to electrical energy

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Correct Option: D
Explanation:

Electric generator, also called dynamo, any machine that converts mechanical energy to electricity for transmission and distribution over power lines to domestic, commercial, and industrial customers. Generators also produce the electrical power required for automobiles, aircraft, ships, and trains.A feature common to both AC and DC generator is Mechanical energy is converted to electrical energy

In an AC generator, the rate of change of magnetic flux through the coil is maximum when the angle between the plane of the coil and the lines of force is

physics effects of electric current electric generator ac generator magnetic effects of electric current

  1. $0^0$

  2. $60^0$

  3. $30^0$

  4. $90^0$

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Correct Option: A
Explanation:

In an AC generator,  Magnetic flux $= NAB\sin\phi$

And, the rate of change of magnetic flux through the coil $(\dfrac{\mathrm{d}\phi }{\mathrm{d} t})$ $= NAB\omega\cos\phi$
So, the rate of change of magnetic flux through the coil is maximum when  $NAB\omega\cos\phi$ is maximum
$\Rightarrow \cos\phi$ is maximum
$\Rightarrow \cos\phi = 1$
$\Rightarrow \phi = 0^0$
Therefore, A is correct option.