Question

Which of the following statements is true?
A. The presence of a large magnetic flux through a coil maintains a current in the coil if the circuit is continuous.
B. A coil of a metal wire kept stationary in a non-uniform magnetic field has an e.m.f. induced in it.
C.  A charged particle enters a region of uniform magnetic field at an angle of \[{85^o}\] to the magnetic lines of force; the path of the particle is a circle.
D.  There is no change in the energy of a charged particle moving in a magnetic field although a magnetic force is acting on it.

Answer 1

Hint: In the given question, we need to determine the correct statement from the given set of statements. For this, we need to check each and every statement one by one.



Complete answer:
We know that since the induced current is generated by changes in magnetic flux, the existence of magnetic flux alone is insufficient to induce current in a coil. Thus, option A is incorrect.

Also, if a metal wire coil is kept steady in a non-uniform magnetic field, the magnetic flux related to the coil does not change. As a result, no emf will be produced by the coil. Hence, option B is also incorrect.

We can say that a particle must be tangential to the magnetic field lines in order to make a circle. As a result, it will not make a circular path here. As a result, the option C is false.

Here, the magnetic field can vary velocity (as direction changes in circular path )but not speed, therefore kinetic energy remains unchanged. So, option D is the correct option.

Therefore, the correct option is (D).



Note:Many students make mistakes in writing the solution part. That means, they may explain the only correct option. But it is necessary to explain all the given options.