Most Important Selected Qs for JEE AdvancedPhysicsElectromagnetic Induction
Inside a very long solenoid of radius R, consider the triangular circuit A B C as shown in figure. Axis of solenoid is perpendicular to the plane of paper. If the magnetic field inside the solenoid changes at the rate dB / dt , then the magnitude of induced emf (A B=B C and A C=2 R)
Options
- Ain the triangular circuit A B C is R^2 | d B d t |
- Bin the triangular circuit A B C is R^2 2 | d B d t |
- Cbetween the ends of wire A B is R^2 2 | d B d t | , if A C and B C were removed from the circuit
- Dbetween the ends of wire B C is R^2 2 | d B d t | , if A C and A B were removed from the circuit,
Correct answer
D. between the ends of wire B C is R^2 2 | d B d t | , if A C and A B were removed from the circuit,
Step-by-step solution
Faraday's law induced e.m.f. =- rate of change of magnetic flux Inside the solenoid, flux = B Area where B is the magnetic flux density Induced e.m.f. =- d d t (B Area )=- Area d B d t =-R^2 d B d t since area of triangle A B C is R^2 . (2) the important point is that a changing magnetic field induces a circulating electric field (from which we derive the induced e.m.f.). in other words, there are no radial components of electric field (radiating outwards or inwards) so that no e.m.f is actually induced in the leng