हिंदी

State the condition at which we say the two coils kept close to each other are perfectly coupled with each other. - Physics

Advertisements
Advertisements

प्रश्न

State the condition at which we say the two coils kept close to each other are perfectly coupled with each other. 

एक पंक्ति में उत्तर
Advertisements

उत्तर

When the coefficient of coupling (K) is 1, then the two coils kept close to each other are said to be perfectly coupled with each other. 

shaalaa.com
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 12: Electromagnetic Induction - Very Short Answer

APPEARS IN

एससीईआरटी महाराष्ट्र Physics [English] 12 Standard HSC
अध्याय 12 Electromagnetic Induction
Very Short Answer | Q 3

वीडियो ट्यूटोरियलVIEW ALL [1]

संबंधित प्रश्न

The magnetic flux through a loop varies according to the relation Φ = 8t2 + 6t + C, where ‘C’ is constant, 'Φ' is in milliweber and 't' is in second. What is the magnitude of induced e.m.f. in the loop at t = 2 seconds.


A metal rod `1/sqrtpi `m long rotates about one of its ends perpendicular to a plane whose magnetic induction is 4 x 10-3 T. Calculate the number of revolutions made by the rod per second if the e.m.f. induced between the ends of the rod is 16 mV.


The phenomenon of electromagnetic induction is


A line charge λ per unit length is lodged uniformly onto the rim of a wheel of mass M and radius R. The wheel has light non-conducting spokes and is free to rotate without friction about its axis (Figure). A uniform magnetic field extends over a circular region within the rim. It is given by,

B = − B0 k (r ≤ a; a < R)

= 0 (otherwise)

What is the angular velocity of the wheel after the field is suddenly switched off?


The magnetic flux through a loop is varying according to a relation `phi = 6t^2 + 7t + 1` where `phi` is in milliweber and t is in second. What is the e.m.f. induced in the loop at t = 2 second?


What is electromagnetic induction?


A circular coil of cross-sectional area 200 cm2 and 20 turns is rotated about the vertical diameter with angular speed of 50 rad s−1 in a uniform magnetic field of magnitude 3.0 × 10−2T. Calculate the maximum value of the current in the coil.


 How does an electromagnet differ forma permanent magnet?  

 


 Explain why, the core of an electromagnet should be of soft iron and not of steel. 


Write some of the important uses of electromagnets. 


State whether the following statement are true or false: 

 A generator works on the principle of electromagnetic induction. 


When a wire is moved up and down in a magnetic field, a current is induced in the wire. What is this phenomenon known as?


How is the working of an electric bell affected, if alternating current be used instead of direct current?


Describe one experiment to demonstrate the phenomenon of electromagnetic induction.


In which of the following case does the electromagnetic induction occur?

A loop of wire is held near a magnet.


Name and state the law which determines the direction of induced current.

or

State Fleming’s right-hand rule.


Welders wear special glass goggles while working. Why? Explain.


A light metal disc on the top of an electromagnet is thrown up as the current is switched on. Why? Give reason.


Show diagrammatically how an alternating emf is generated by a loop of wire rotating in a magnetic field. Write the expression for the instantaneous value of the emf induced in the rotating loop.


Consider the energy density in a solenoid at its centre and that near its ends. Which of the two is greater?


A conducting rod is moved with a constant velocity v in a magnetic field. A potential difference appears across the two ends _____________ .


The switches in figure (a) and (b) are closed at t = 0 and reopened after a long time at t = t0.

(a) The charge on C just after t = 0 is εC.
(b) The charge on C long after t = 0 is εC.
(c) The current in L just before t = t0 is ε/R.
(d) The current in L long after t = t0 is ε/R.


Draw a simple labeled diagram of a step-down transformer.


The following diagram shows a fixed coil of several turns connected to a center zero galvanometer G and a magnet NS which can move in the direction shown in the diagram.

  1. Describe the observation in the galvanometer if
    1. The magnet is moved rapidly,
    2. The magnet is kept still after it has moved into the coil
    3. The magnet is then rapidly pulled out the coil.
  2. How would the observation in (i) of part (a) change if a more powerful magnet is used?


Why do you mean by turns ratio of a transformer? Can it work with D.C.?

Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.

 D.C. motor ______.


A transformer has 400 turns in the primary winding and 10 turns in the secondary winding. The primary e.m.f. is 250 V and the primary current is 2.0 A. calculate:
(a) The secondary voltage,
(b) The secondary current, assuming 100% efficiency.


List some of the practical applications of an electromagnet.


Why soft iron is preferred to be used as the core of the electromagnet of an electric bell?


The diagram shows a rectangular coil ABCD, suspended freely between the concave pole pieces of a permanent horseshoe magnet, such that the plane of the coil is parallel to the magnetic field.

  1. State your observation when the current is switched on.
  2. Give an explanation for your observation in (i).
  3. State the rule, which will help you to find the motion of rotation of the coil.
  4. In which position will the coil ultimately come to rest?
  5. State four ways of increasing the magnitude of force acting on the coil.

Observe the given figure of Fleming’s Right Hand Rule and write the labels of A and B correctly.


Write the two names in the following diagram.

Fleming’s right hand rule.


An induced current of 2.5 mA flows through a single conductor of resistance 100 Ω. Find out the rate at which the magnetic flux is cut by the conductor.


A coil of 200 turns carries a current of 4 A. If the magnetic flux through the coil is 6 x 10-5 Wb, find the magnetic energy stored in the medium surrounding the coil.


A generator has an e.m.f. of 440 Volt and internal resistance of 4000 hm. Its terminals are connected to a load of 4000 ohm. The voltage across the load is ______.


In electromagnetic induction, the induced charge is independent of ______.

The instrument that use to defect electric current in the circuit is known as ____________.


We can induce the current in a coil by ____________.


Ansari Sir was demonstrating an experiment in his class with the setup as shown in the figure below.

A magnet is attached to a spring. The magnet can go in and out of the stationary coil. He lifted the Magnet and released it to make it oscillate through the coil.
Based on your understanding of the phenomenon, answer the following question.

What is the principle which Ansari Sir is trying to demonstrate?


Ansari Sir was demonstrating an experiment in his class with the setup as shown in the figure below.

A magnet is attached to a spring. The magnet can go in and out of the stationary coil. He lifted the Magnet and released it to make it oscillate through the coil.
Based on your understanding of the phenomenon, answer the following question.

What will be observed when the Magnet starts oscillating through the coil. Explain the reason behind this observation.


Induced current flows through a coil ______.


Which of the following instruments works by electromagnetic induction?


Sea turtles return to their birth beach many decades after they were born due to ______.


A galvanometer is an instrument that can detect the presence of a current in a circuit.


The working of a dynamo is based on the principle of


A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figure

Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field `vec"B"` pointing into the page. An external agent pulls the bar to the left at a constant speed v. The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is:


The primary of a transformer has 400 turns while the secondary has 2000 turns. If the power output from the secondary at 1000 Vis 12 kW, what is the primary voltage?


In the current carrying conductor (AOCDEFG) as shown, the magnetic induction at point O is ______.

(R1 and R2 are radii of CD and EF respectively. l = current in the loop, μ0 = permeability of free space)

 


Which type of force is experienced by a moving charge in a magnetic field?


When an electric current is passed through a wire or a coil, a magnetic field is produced. Is the reverse phenomenon possible i.e, can a magnetic field produce an electric current? Explain with the help of an appropriate example.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×