Answer:
C. 0.25 m
Explanation:
Given;
current flow in the solenoid, I = 6.0 A
number of turns of the solenoid, N = 180 turns
the resistance of the circuit, R = 17 Ω
change in the magnetic field, dB/dt = 3.0 T/s
The emf of the circuit is given by;
V = IR
V = 6 x 17
V = 102 Volts
Magnitude of induced emf is given by;
[tex]E = N(\frac{dB}{dt} )A[/tex]
Where;
A is area of the solenoid
[tex]E = N(\frac{dB}{dt} )A\\\\A = \frac{E}{N(\frac{dB}{dt} )} \\\\A = \frac{102}{180 *3} \\\\A = 0.18889 \ m^2[/tex]
Area of the circular solenoid is given by;
A = πr²
where;
r is radius of the solenoid
[tex]r = \sqrt{\frac{A}{\pi} }\\\\r = \sqrt{\frac{0.18889}{\pi} }\\\\r = 0.25 \ m[/tex]
Therefore, the correct option is C. 0.25 m
