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A circular coil begins completely outside any magnetic field, and then during the next 10 sec. it moves completely into a uniform 15T magnetic field. Assuming that the plane of the loop and the direction of motion are both perpendicular to the magnetic field, the magnitude of induced emf in the coil with 25 loops and radius of 7 cm is
  • a)
    0 volt
  • b)
    0.58 volt
  • c)
    1.2 volt
  • d)
    0.23 volt
Correct answer is option 'B'. Can you explain this answer?
Verified Answer
A circular coil begins completely outside any magnetic field, and then...
Since the loop begins outside of any magnetic field, therefore initial magnetic flux is zero.
The final flux is given by

Using Faraday’s law, emf induced in the loop is given by


∴ 
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Most Upvoted Answer
A circular coil begins completely outside any magnetic field, and then...

Given Data:
- Number of loops (N) = 25
- Magnetic field strength (B) = 15T
- Radius of the coil (r) = 7 cm = 0.07 m
- Time taken to move into the magnetic field (t) = 10 sec

Formula for induced emf:
The induced emf in a circular coil moving into a magnetic field is given by the formula:
\[ \varepsilon = -N \cdot A \cdot \frac{dB}{dt} \]
Where:
- \( \varepsilon \) = induced emf
- N = number of loops
- A = area of the coil
- \( \frac{dB}{dt} \) = rate of change of magnetic field strength

Area of the coil:
The area of the circular coil is given by:
\[ A = \pi r^2 \]

Rate of change of magnetic field strength:
Since the coil is moving into the magnetic field, the rate of change of magnetic field strength can be calculated as:
\[ \frac{dB}{dt} = \frac{B_{final} - B_{initial}}{t} \]
\[ \frac{dB}{dt} = \frac{15T - 0T}{10sec} = 1.5 T/sec \]

Calculating induced emf:
Substitute the values into the formula for induced emf:
\[ \varepsilon = -25 \cdot \pi \cdot (0.07)^2 \cdot 1.5 \]
\[ \varepsilon = -25 \cdot \pi \cdot 0.0049 \cdot 1.5 \]
\[ \varepsilon = -25 \cdot 0.0153 \cdot \pi \]
\[ \varepsilon = -0.575 \pi \]
\[ \varepsilon \approx -1.80 V \]

Therefore, the magnitude of the induced emf in the coil is approximately 0.58 volts. This negative sign indicates that the direction of the induced current is such that it opposes the change in magnetic flux.
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A circular coil begins completely outside any magnetic field, and then during the next 10 sec. it moves completely into a uniform 15Tmagnetic field. Assuming that the plane of the loop and the direction of motion are both perpendicular to the magnetic field, the magnitude of induced emf in the coil with 25 loops and radius of 7 cm isa)0 voltb)0.58 voltc)1.2 voltd)0.23 voltCorrect answer is option 'B'. Can you explain this answer?
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A circular coil begins completely outside any magnetic field, and then during the next 10 sec. it moves completely into a uniform 15Tmagnetic field. Assuming that the plane of the loop and the direction of motion are both perpendicular to the magnetic field, the magnitude of induced emf in the coil with 25 loops and radius of 7 cm isa)0 voltb)0.58 voltc)1.2 voltd)0.23 voltCorrect answer is option 'B'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about A circular coil begins completely outside any magnetic field, and then during the next 10 sec. it moves completely into a uniform 15Tmagnetic field. Assuming that the plane of the loop and the direction of motion are both perpendicular to the magnetic field, the magnitude of induced emf in the coil with 25 loops and radius of 7 cm isa)0 voltb)0.58 voltc)1.2 voltd)0.23 voltCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A circular coil begins completely outside any magnetic field, and then during the next 10 sec. it moves completely into a uniform 15Tmagnetic field. Assuming that the plane of the loop and the direction of motion are both perpendicular to the magnetic field, the magnitude of induced emf in the coil with 25 loops and radius of 7 cm isa)0 voltb)0.58 voltc)1.2 voltd)0.23 voltCorrect answer is option 'B'. Can you explain this answer?.
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