State Any Two Causes of Energy Loss in Actual Transformers. - Physics


State any two causes of energy loss in actual transformers.



Following are the two cause of energy loss:

  1. Iron loss: Loss in the bulk of iron core due to the induced eddy currents. It is minimised by using thin laminated core.
  2. Current flowing through the primary and secondary coils will generate heat. Low resistance copper wires is used to reduce this effect.
Concept: Eddy Currents
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2014-2015 (March) Patna Set 2

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 How are eddy currents produced ?

Describe briefly three main useful application of eddy currents ?

If the magnetic field outside a copper box is suddenly changed, what happens to the magnetic field inside the box? Such low-resistivity metals are used to form enclosures which shield objects inside them against varying magnetic fields.

Metallic (nonferromagnetic) and nonmetallic particles in a solid waste may be separated as follows. The waste is allowed to slide down an incline over permanent magnets. The metallic particles slow down as compared to the nonmetallic ones and hence are separated. Discuss the role of eddy currents in the process.

A metallic bob A oscillates through the space between the poles of an electromagnet (See the figure). The oscillations are more quickly damped when the circuit is on, as compared to the case when the circuit is off. Explain.

A metal sheet is placed in front of a strong magnetic pole. A force is needed to ______________ .
(a) hold the sheet there if the metal is magnetic
(b) hold the sheet there if the metal is nonmagnetic
(c) move the sheet away from the pole with uniform velocity if the metal is magnetic
(d) move the sheet away from the pole with uniform velocity if the metal is nonmagnetic.
Neglect any effect of paramagnetism, diamagnetism and gravity.

State applications of eddy currents.

In which of the following devices, the eddy current is not used ______ 

Why and where are eddy currents are undesirable? How are they minimized? 

How is Eddy current produced? How do they flow in a conductor?

Give the uses of Foucault current.

Certain galvanometers have a fixed core made of nonmagnetic metallic material, when the coil oscillates, ...A... generated in the core ...B... the motion and bring the coil to rest ...C...
Here, A, B and C refer to ______.

Induction furnace make use of ______.

Which of the following is not the application of eddy currents?

Identify the wrong statement.

What are eddy currents?

A constant retarding force of50 N is applied to a body of mass 20 kg moving initially with a speed of 15 ms-1. How long does the body take to stop?

Two simple pendula of length L and 4L are pulled aside to the right and are at rest so that they make an angle 30° with the vertical. They are then released simultaneously at time t = 0. The time after which they will be in phase is ______.

If the length of a simple pendulum increases by 5%, then its period shall increase by ______.

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Which one is not an application of eddy current?

Eddy currents are also known as ______

A metal plate is getting heated. It can be because ______.

  1. a direct current is passing through the plate.
  2. it is placed in a time varying magnetic field.
  3. it is placed in a space varying magnetic field, but does not vary with time.
  4. a current (either direct or alternating) is passing through the plate.

Consider a metallic pipe with an inner radius of 1 cm. If a cylindrical bar magnet of radius 0.8 cm is dropped through the pipe, it takes more time to come down than it takes for a similar unmagnetised cylindrical iron bar dropped through the metallic pipe. Explain.


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