English

What is electromagnetic induction? - Physics

Advertisements
Advertisements

Question

What is electromagnetic induction?

One Line Answer

Solution

The phenomenon of producing an induced e.m.f in a conductor or conducting coil due to changing magnetic flux is called electromagnetic induction.

shaalaa.com
  Is there an error in this question or solution?
Chapter 12: Electromagnetic induction - Exercises [Page 286]

APPEARS IN

Balbharati Physics [English] 12 Standard HSC Maharashtra State Board
Chapter 12 Electromagnetic induction
Exercises | Q 2. i) (a) | Page 286
Samacheer Kalvi Physics - Volume 1 and 2 [English] Class 12 TN Board
Chapter 4 Electromagnetic Induction And Alternating Current
Evaluation | Q II. 1. | Page 260
Selina Physics [English] Class 10 ICSE
Chapter 10 Electro-Magnetism
Exercise 10 (C) 1 | Q 1.1 | Page 258
Frank Physics - Part 2 [English] Class 10 ICSE
Chapter 4 Current Electricity
Exercise 4.3 i | Q 2 | Page 205
ICSE Physics [English] Class 10
Chapter 9 Magnetic Effect of Current
Short Answers | Q 38

Video TutorialsVIEW ALL [1]

RELATED QUESTIONS

A solenoid of length 1.5 m and 4 cm in diameter possesses 10 turns per metre. A current of 5 A is flowing through it. The magnetic induction at a point inside the solenoid along the axis is ............................. .

0 = 4π × 10-7 Wb/Am)

  1. π  × 10-5 T
  2. 2π × 10-5 T
  3. 3π × 10-5 T
  4. 4π × 10-5 T

The device used for producing electric current is called _________.


State Fleming’s right-hand rule.


When a bar magnet is pushed towards (or away) from the coil connected to a galvanometer, the pointer in the galvanometer deflects. Identify the phenomenon causing this deflection and write the factors on which the amount and direction of the deflection depends. State the laws describing this phenomenon.


Explain different ways to induce current in a coil.


The phenomenon of electromagnetic induction is


 Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.


A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is 1 cm s−1 in a direction normal to the

  1. longer side,
  2. shorter side of the loop? 

For how long does the induced voltage last in each case?


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)`


Name a common device that uses electromagnets.


When an electric current is passed through any wire, a magnetic field is produced around it. Then why an electric iron connecting cable does not attract nearby iron objects when electric  current switched on through it?


State three ways in which the strength of an electromagnet can be increased.


 State the factors on which the strength of an electromagnet depends. How does it depend on these factors?


Write some of the important uses of electromagnets. 


The most suitable material for making the core of an electromagnet is:

(a) soft iron
(b) brass
(c) aluminium
(d) steel


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?


 What do you understand by the term "electromagnetic induction"? Explain with the help of a diagram. 


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


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


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


When Puja, a student of 10th class, watched her mother washing clothes in the open, she observed coloured soap bubbles and was curious to know why the soap bubbles appear coloured. In the evening when her father, an engineer by profession, came home, she asked him this question. Her father explained to her the basic phenomenon of physics due to which the soap bubbles appear coloured.
(a) What according to you are the values displayed by Puja and her father?
(b) State the phenomenon of light involved in the formation of coloured soap bubbles.


The coil of a moving-coil galvanometer keeps on oscillating for a long time if it is deflected and released. If the ends of the coil are connected together, the oscillation stops at once. Explain.


A conducting square loop of side l and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A uniform and constant magnetic field Bexists along the perpendicular to the plane of the loop as shown in figure. The current induced in the loop is _____________ .


Figure shows a wire sliding on two parallel, conducting rails placed at a separation l. A magnetic field B exists in a direction perpendicular to the plane of the rails. What force is necessary to keep the wire moving at a constant velocity v?


Figure shows a long U-shaped wire of width l placed in a perpendicular magnetic field B. A wire of length l is slid on the U-shaped wire with a constant velocity v towards right. The resistance of all the wires is r per unit length. At t = 0, the sliding wire is close to the left edge of the U-shaped wire. (a) Calculate the force needed to keep the sliding wire moving with a constant velocity v. (b) If the force needed just after t = 0 is F0, find the time at which the force needed will be F0/2.0


Can you find the magnitude of current using Fleming's right hand rule?

State Fleming's right hand rule.

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?


Draw and label the diagram of a simple D.C. motor.
(a) Explain the rotation of the coil, giving a reason for your answer.
(b) How can you reverse the direction of rotation of the armature?
(c) How can you increase the speed of rotation of the motor?


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.

Transformer______.


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.


Name the following diagram and explain the concept behind it.


State Fleming’s Right Hand Rule.


List two ways of increasing the strength of an electromagnet if the material of the electromagnet is fixed.


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


Draw a labelled diagram to make an electromagnet from a soft iron bar. Mark the polarity at its ends in your diagram. What precaution would you observe while making it?


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


The right-hand thumb rule is also called _______ rule.


Write the two names in the following diagram.

Fleming’s right hand rule.


An electron moves on a straight-line path XY as shown in the figure. The coil abcd is adjacent to the path of the electron. What will be the direction of the current, if any, induced in the coil?


A thin semi-circular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in the figure.

The potential difference developed across the ring when its speed v , is


What for an inductor is used? Give some examples.


Give an illustration of determining direction of induced current by using Lenz’s law.


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


A square coil of side 30 cm with 500 turns is kept in a uniform magnetic field of 0.4 T. The plane of the coil is inclined at an angle of 30° to the field. Calculate the magnetic flux through the coil.


A straight metal wire crosses a magnetic field of flux 4 mWb in a time 0.4 s. Find the magnitude of the emf induced in the wire.


The magnetic flux passing through a coil perpendicular to its plane is a function of time and is given by OB = (2t3 + 4t2 + 8t + 8) Wb. If the resistance of the coil is 5 Ω, determine the induced current through the coil at a time t = 3 second.


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 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.


A coil of 200 turns carries a current of 0.4 A. If the magnetic flux of 4 mWb is linked with each turn of the coil, find the inductance of the coil.


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 ______

     


Metal rings P and Q are lying in the same plane, where current I is increasing steadily. The induced current in metal rings is shown correctly in figure.


A layer of atmosphere that reflects medium frequency radio waves which is ineffective during night, is ______.


A cylindrical bar magnet is kept along the axis of a circular coil. If the magnet is rotated about its axis, then ____________.


The condition for the praenomen of electromagnetic induction is that there must be a relative motion between ____________.


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


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?


For making a strong electromagnet the material of the core should be ______.


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


A 0.4 m wire, stretched horizontally, carries an electric current of 15 A, in a magnetic field whose magnetic field intensity is 0.1 N/Am. What is the magnitude of the wire?


A conductor of length 50 cm carrying a current of 5 A is placed perpendicular to a magnetic field of induction 2×10 -3T. Find the force on the conductor.


Which of the following phenomena makes use of electromagnetic induction?


An expression for oscillating electric field in a plane electromagnetic wave is given as Ez = 300 sin(5π × 103x - 3π × 1011t)Vm-1 Then, the value of magnetic field amplitude will be ______. (Given: speed of light in Vacuum c = 3 × 108 ms-1)


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×