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

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 device used for producing electric current is called _________.


State Fleming’s right-hand rule.


State three differences between direct current and alternating current.


Explain different ways to induce current in a coil.


It is desired to measure the magnitude of field between the poles of a powerful loud speaker magnet. A small flat search coil of area 2 cm2 with 25 closely wound turns, is positioned normal to the field direction, and then quickly snatched out of the field region. Equivalently, one can give it a quick 90° turn to bring its plane parallel to the field direction. The total charge flown in the coil (measured by a ballistic galvanometer connected to coil) is 7.5 mC. The combined resistance of the coil and the galvanometer is 0.50 Ω. Estimate the field strength of magnet.


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?


What is electromagnetic induction?


If ‘R’ is the radius of dees and ‘B’ be the magnetic field of induction in which positive charges (q) of mass (m) escape from the cyclotron, then its maximum speed (vmax) is _______.

A) `(qR)/(Bm)`

B)`(qm)/(Br)`

C) `(qBR)/m`

D) `m/(qBR)`


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.


What is an electromagnet? Describe the construction and working of an electromagnet with the help of a labelled diagram.


 Explain why, an electromagnet is called a temporary magnet.


The north-south polarities of an electromagnet can be found easily by using:

(a) Fleming's right-hand rule
(b) Fleming's left-hand rule
(c) Clock face rule
(d) Left-hand thumb rule


State whether the following statement are true or false: 

A motor works on the principle electric generator? 


An induced current is produced when a magnet is moved into a coil. The magnitude of induced current does not depend on:  

(a) the speed with which the magnet is moved
(b) the number of turns of the coil
(c) the resistivity of the wire of the coil
(d) the strength of the magnet


Describe one experiment to demonstrate the phenomenon of electromagnetic induction.


In which of the following case does the electromagnetic induction occur?
The current is stopped in a wire held near a loop of wire .


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.


Welders wear special goggles or face masks with glass windows to protect their eyes from electromagnetic radiations. Name the radiations and write the range of their frequency.


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


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


The diagram 10 shows two coils X and Y. The coil X is connected to a battery S and a key K. The coil Y is connected to a galvanometer G.

When the key K is closed. State the polarity
(i)At the end of the coil X,
(ii)At the end C of the coil Y,
(iii)At the end C of the coil Y if the coil Y is (a) Moved towards the coil X, (b) Moved away from the coil X.


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?


Fig. shows a simple form of an A.C. generator.

(a) Name the parts labeled A and B.
(b) What would be the effect of doubling the number of turns on the coil if the speed of rotation remains unchanged?
(c) Which of the output terminals is positive if the coil is rotating in the
direction shown in the diagram (anticlockwise)?
( d ) What is the position of the rotating coil when p.d. across its ends is zero? Explain why p.d. is zero when the coil is at this position .
(e) Sketch a graph showing how the p.d. across the ends of the rotating coil varies with time for an A.C. dynamo.
( f) On th e same sheet of paper and vertically below the first graph using the same time scale, sketch graphs to show the effect of
(i) Doubling the speed of rotation and at the same time keeping
the field and the number of turns constant,
(ii ) Doubling the number of turns on the coil and at the same time
doubling the speed of rotation of the coil, keeping th e speed
constant.


Answer the following:

State the principles of the electric motor and electric generator. 


Draw a labelled diagram to show how an electromagnet is made.


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.

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


Fleming's left hand rule : electric current : : Fleming's right hand rule : _______


Find the odd one out and give its explanation.


Write Fleming’s right hand thumb rule with the help of diagram.


State Lenz’s law.


State Fleming’s right-hand rule.


Show that Lenz’s law is in accordance with the law of conservation of energy.


Obtain an expression for motional emf from Lorentz force.


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 50 cm long solenoid has 400 turns per cm. The diameter of the solenoid is 0.04 m. Find the magnetic flux linked with each turn when it carries a current of 1 A.


Using Lenz’s law, predict the direction of induced current in conducting rings 1 and 2 when the current in the wire is steadily decreasing.


Shown in the figure below is a metre bridge set up with null deflection in the galvanometer. The value of the unknown resistance R is ______

     


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

For magnetic breaking in trains, strong electromagnets are situated above the rails in some electrically powered trains. When the electromagnets are activated, the ...A... induced in the rails oppose the motion of the train. As there are no ... B... linkages, the ...C... effects is smooth. Here, A, B and C refer to ______.

What should be the core of an electromagnet?


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.

Consider the situation where the Magnet goes in and out of the coil. State two changes which could be made to increase the deflection in the galvanometer.


If the sun radiates energy at the rate of 3.6 × 1033 ergs/sec the rate at which the sun is loosing mass is given by ______.


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 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:


One solenoid is centered inside another. The outer one has a length of 50.0 cm and contains 6750 coils, while the coaxial inner solenoid is 3.0 cm long and π cm2 in area and contains 150 coils. The current in the outer solenoid is changing at 3000 A/s. The emf induced in the inner solenoid is ______ V.

(Round off to two decimal places.)


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?


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×