Use Lenz’s law to determine the direction of induced current in the situations described by Fig.: - Physics

Advertisements
Advertisements
Answer in Brief

Use Lenz’s law to determine the direction of induced current in the situations described by Fig.:

(a) A wire of irregular shape turning into a circular shape;

(b) A circular loop being deformed into a narrow straight wire.

Advertisements

Solution

According to Lenz’s law, the direction of the induced emf is such that it tends to produce a current that opposes the change in the magnetic flux that produced it.

(a) When the shape of the wire changes, the flux piercing through the unit surface area increases. As a result, the induced current produces an opposing flux. Hence, the induced current flows along adcb.

(b) When the shape of a circular loop is deformed into a narrow straight wire, the flux piercing the surface decreases. Hence, the induced current flows along a'd'c'b'.

  Is there an error in this question or solution?
Chapter 6: Electromagnetic Induction - Exercise [Page 230]

APPEARS IN

NCERT Physics Class 12
Chapter 6 Electromagnetic Induction
Exercise | Q 6.2 | Page 230
NCERT Physics Class 12
Chapter 6 Electromagnetic Induction
Exercise | Q 2 | Page 230

Video TutorialsVIEW ALL [1]

RELATED QUESTIONS

State Lenz's law. Illustrate, by giving an example, how this law helps in predicting the direction of the current in a loop in the presence of a changing magnetic flux.


Describe a simple experiment (or activity) to show that the polarity of emf induced in a coil is always such that it tends to produce a current which opposes the change of magnetic flux that produces it.


What is the direction of induced currents in metal rings 1 and 2 when current I in the wire is increasing steadily? 


Show that Lenz's law is a consequence of conservation of energy.


Predict the directions of induced currents in metal rings 1 and 2 lying in the same plane where current I in the wire is increasing steadily.


Predict the direction of induced current in a metal ring when the ring is moved towards a straight conductor with constant speed v. The conductor is carrying current I in the direction shown in the figure.


Predict the direction of induced current in metal rings 1 and 2 when current I in the wire is steadily decreasing?


A short magnet is moved along the axis of a conducting loop. Show that the loop repels the magnet if the magnet is approaching the loop and attracts the magnet if it is going away from the loop.


The battery discussed in the previous question is suddenly disconnected. Is a current induced in the other loop? If yes, when does it start and when does it end? Do the loops attract each other or repel?


A pivoted aluminium bar falls much more slowly through a small region containing a magnetic field than a similar bar of an insulating material. Explain.


Consider the situation shown in figure. If the switch is closed and after some time it is opened again, the closed loop will show ____________ .


A bar magnet is released from rest along the axis of a very long, vertical copper tube. After some time the magnet ____________ .


Two circular loops of equal radii are placed coaxially at some separation. The first is cut and a battery is inserted in between to drive a current in it. The current changes slightly because of the variation in resistance with temperature. During this period, the two loops _______________ .


A bar magnet is moved along the axis of a copper ring placed far away from the magnet. Looking from the side of the magnet, an anticlockwise current is found to be induced in the ring. Which of the following may be true?
(a) The south pole faces the ring and the magnet moves towards it.
(b) The north pole faces the ring and the magnet moves towards it.
(c) The south pole faces the ring and the magnet moves away from it.
(d) The north pole faces the ring and the magnet moves away from it.


Consider the situation shown in figure. If the closed loop is completely enclosed in the circuit containing the switch, the closed loop will show _______________ .


Lenz’s law is a consequence of the law of conservation of ______.


2 A 40 kg boy whose legs are 4 cm in area and 50 cm long falls through a height of 2 m without breaking his leg bones. If the bones can withstand stress of 0.9 x 108 N/m2. The Young's modulus for the material of the bone is ______.


Young's modulus for aluminium is 7 × 1010 Pa. The force needed to stretch an aluminium wire of diameter 2 mm and length 800 mm by 1 mm is ______.


A bar magnet is dropped through a copper ring acceleration of magnet is


Energy dissipate in LCR circuit in


For a coil having L = 2 mH, current flows at the rate of 10-3 AIS. The e.m.f induced is


Lenz's law gives ______


A wire in the form of a tightly wound solenoid is connected to a DC source, and carries a current. If the coil is stretched so that there are gaps between successive elements of the spiral coil, will the current increase or decrease? Explain.


A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating: It is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to:


Share
Notifications



      Forgot password?
Use app×