Tag: physics

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Multiple choice physics common machines kinds of simple machines inclined plane, wedge, screw and wheel and axle types of simple machines

As the inclination of the screw increases, the distance between the threads

  1. increases

  2. decreases

  3. remains the same

  4. may increase or decrease
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pitch of a screw is the distance between threads. Increasing the inclination (lead angle) for a fixed diameter generally results in a steeper thread, which corresponds to a smaller distance between threads for a given rotation.

Multiple choice physics wave optics refraction of water waves reflection and refraction at plane surfaces theories on light

Which of the following statement is incorrect about the Raman effect?

  1. Raman effect can be seen by passing a monochromatic beam of light through benzene

  2. During scattering, the wavelength of the light used may change

  3. The wavelength of the monochromatic light used to show the Raman effect is approximately $4358$ $\overset{o}{A}$

  4. In Raman scattering the wavelength of the scattered light is the same as that of the incident light
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The Raman effect involves inelastic scattering of light, meaning the wavelength of the scattered light is different from the incident light (Stokes and anti-Stokes lines).

Multiple choice eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

Identify the wrong statement

  1. Eddy currents are produced in a steady magnetic field

  2. Eddy currents can be minimized by using laminated core

  3. Induction furnace uses eddy current to produce heat

  4. Eddy current can be used to produce breaking force in moving trains
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eddy currents comes in picture only when there is change in linked magnetic flux. 

They can be created when a conductor is moving through a magnetic field, or when the magnetic field surrounding a stationary conductor is varying i.e. anything which results in the conductor experiencing a change in the intensity or direction of a magnetic field can produce eddy currents.

Thus  $A$ is the correct option.

Multiple choice eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

Identify the wrong statement.

  1. Eddy currents are produced in a steady magnetic field.

  2. Eddy currents can be minimized by using laminated core.

  3. Induction furnace uses eddy current to produce heat.

  4. Eddy current can be used to produce breaking force in moving trains.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eddy currents comes in picture only when there is change in linked magnetic flux. Thus statement A is wrong.

Multiple choice eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

Which of the following law follows when eddy currents are generated?

  1. Lenz's law

  2. Gauss's law

  3. Both A and B

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field.By Lenz's law, an eddy current creates a magnetic field that opposes the change in the magnetic field that created it, and thus eddy currents react back on the source of the magnetic field.Lenz law, the current swirls in such a way as to create a magnetic field opposing the change; for this to occur in a conductor, electrons swirl in a plane perpendicular to the magnetic field.

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Multiple choice eddy currents motional emf electromagnetic induction electromagnetic induction and alternating currents physics

Which of the following is true in context of Eddy currents?

  1. By Lenz's law, an eddy current creates a magnetic field that opposes the magnetic field that created it.

  2. Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction

  3. Eddy currents are a cause of energy loss in alternating current (AC) inductors, transformers, electric motors and generators etc.

  4. All of the above 
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 Eddy currents are loops of electrical current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction,are a cause of energy loss in alternating current (AC) inductors, transformers, electric motors and generators etc.

By Lenz's law, an eddy current creates a magnetic field that opposes the magnetic field that created it.
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