Question 20

A coil is placed in magnetic field such that plane of coil is perpendicular to the direction of magnetic field. The magnetic flux through a coil can be changed:
A. By changing the magnitude of the magnetic field within the coil.
B. By changing the area of coil within the magnetic field.
C. By changing the angle between the direction of magnetic field and the plane of the coil.
D. By reversing the magnetic field direction abruptly without changing its magnitude.
Choose the most appropriate answer from the options given below:

Solution

$$\Phi = B \cdot A \cdot \cos \phi$$

Statement A: Since $$\Phi \propto B$$, any change in the strength of the magnetic field passing through the coil will directly result in a change in the magnetic flux.

Statement B: Since $$\Phi \propto A$$, if the area of the coil within the magnetic field is increased or decreased, the flux will change.

Statement C: Changing the angle between the field and the plane of the coil changes $$\phi$$. This modifies the $$\cos \phi$$ factor, thereby changing the flux (This is the principle used in AC generators).

Statement D: Reversing the magnetic field direction effectively changes the angle $$\phi$$ by $$180^\circ$$ (or changes B to -B). The flux changes from $$\Phi$$ to $$-\Phi$$, resulting in a net change of $$\Delta \Phi = 2\Phi$$.

Hence, all the statements are correct.

Solution

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