Q 26

For a long ideal solenoid having a circular cross-section,the magnetic field strength within the solenoid is given by the equation B(t)= 5.0t T,where t is time in seconds.If the induced electric field outside the solenoid is 1.1 V/m at a distance of 2.0 m from the axis of the solenoid,find the radius of the solenoid.
A) 0.30 m
B) 77 m
C) 0.94 m
D) 9.0 m

Q 27

The coil in a 60-Hz ac generator has 125 turns,each having an area of 3.0 × 10^{-2} m^{2} and is rotated in a uniform 0.12-T magnetic field.What is the peak output voltage of this generator?
A) 170 V
B) 120 V
C) 200 V
D) 110 V
E) 220 V

Q 28

Suppose that you wish to construct a simple ac generator having an output of 12 V maximum when rotated at 60 Hz. A uniform magnetic field of 0.050 T is available. If the area of the rotating coil is
100 cm^{2},how many turns do you need?
A) 8
B) 16
C) 32
D) 64
E) 128