A wire loop is rotated in a magnetic field. Thefrequency of change of ...
This is the case of periodic EMI
From graph, it is clear that direction is
changing once in 1/2 cycle.
View all questions of this test
A wire loop is rotated in a magnetic field. Thefrequency of change of ...
Explanation:
When a wire loop is rotated in a magnetic field, an electromotive force (emf) is induced in the wire due to the magnetic field. The frequency of change of direction of the induced emf depends on the number of times the loop completes a revolution.
Concept of Induced EMF:
According to Faraday's law of electromagnetic induction, the emf induced in a wire loop is directly proportional to the rate of change of magnetic flux through the loop. The magnetic flux is given by the product of the magnetic field strength (B) and the area (A) of the loop.
Change of Direction:
When the wire loop completes one revolution, it changes its direction by 180 degrees. This means that the area vector of the loop changes its direction by 180 degrees with each revolution. As a result, the direction of the magnetic flux through the loop also changes by 180 degrees.
Calculation:
To find the frequency of change of direction of the induced emf, we need to determine how many times the loop completes a revolution.
Let's assume that the loop completes "n" revolutions per second. In one revolution, the direction of the magnetic flux changes by 180 degrees.
So, in "n" revolutions, the direction of the magnetic flux will change by 180n degrees.
To complete one revolution, the direction of the magnetic flux must change by 180 degrees. Therefore, we can write the equation:
180n = 180
Simplifying the equation:
n = 1
This means that the wire loop completes one revolution per second. Therefore, the frequency of change of direction of the induced emf is once per revolution.
Conclusion:
Hence, the correct answer is option 'D' - once per revolution.