Question

QUESTION 18

1. A magnetic field is perpendicular to the plane of a rectangular cable with dimensions 0.15 m x 0.30 m that has 120 turns. To induce an average "emf" of -1.2 V in the cable, the magnetic field is increased from 0.1 T to 1.5 T in a time interval t. Determine t

a. 0.053 s

b. 1.6 s

c. 7.6 s

d. 6.3 s

e. 0.13 s

QUESTION 19

1. When a radio telescope observes a region in the space between two stars, it detects electromagnetic radiation that has a wavelength equal to 0.21 m. Determine the frequency of this radiation.

a. 7.1 x 10 ^ 10 Hz

b. 6.9 x 10 ^ 11 Hz

c. 2.1 x 10 ^ 14 Hz

d. 1.4 x 10 ^ 9 Hz

e. 3.0 x 10 ^ 8 Hz

QUESTION 20

1. A radio station transmits radio waves that radiate uniformly in all directions with power 1.50 x 10 ^ 5 W. Determine the intensity of the waves when received at an antenna located 40.0 km from the transmitting antenna.

a 5.60 x 10 ^ -10 W / m ^ 2

b. 2.98 x 10 ^ -5 W / m ^ 2

c. 9.25 x 10 ^ -7 W / m ^ 2

d. 7.46 x 10 ^ -6 W / m ^ 2

e. 1.17 x 10 ^ -8 W / m ^ 2

Answer 1