Wave 1 has frequency f1 and wavelength 1 . Wave 2 has frequency f2 = 6 f1 and wavelength 2 = 21 . How does the speed v2 of wave 2 compare with the speed v1 of wave 1?
a. v2 = 12v1 b. v2 = 6v1
c. v2 = 1.5v1 d. v2 = v1/6
[Ques. 2] Two long parallel wires 45.6 cm apart are carrying currents of 13.0 A and 23.0 A in the same direction. What is the magnitude of the magnetic field halfway between the wires?
a. 8.77E6 T
b. 3.16E5 T
c. 1.14E5 T
d. 2.02E5 T
e. 4.39E6 T
[Ques. 3] A steel piano string is attached, under tension, at each end to secure posts. When gently struck, a faint note can be detected coming from the string. The string is then cooled by blowing cold air over it and then is struck again. How does the note now detected compare to the previous one.
a. It is the same since the posts don't move.
b. It is at a higher frequency than the original one.
c. It is at a lower frequency than the original one.
d. More than one answer is correct.
[Ques. 4] Niobium metal becomes a superconductor (with electrical resistance equal to zero) when cooled below 9.00 K. If superconductivity is destroyed when the surface magnetic field exceeds 0.100 T, determine the maximum current a 5.31-mm-diameter niobium wire can carry and remain superconducting. (0 = 4 107 Tm/A)
a. 2660 A
b. 423 A
c. 211 A
d. 1330 A
e. 4170 A
[Ques. 5] Equal-wavelength waves of amplitude 0.27 m and 0.13 m interfere with one another. What is the resulting minimum amplitude that can result?
a. 0.13 m
b. 0.14 m
c. 0 m
d. 0.40 m
e. 0.20 m
[Ques. 6] Two long parallel wires 10.0 cm apart carry currents of 3.0 A and 2.9 A in the same direction. Is there any point between the two wires where the magnetic field is zero?
a. yes, midway between the wires
b. yes, 4.9 cm from the 3.0-A wire
c. yes, 5.1 cm from the 3.0-A wire
d. yes, 5.1 cm from the 2.9-A wire
e. no.
[Ques. 7] The superposition principle has to do with which of the following?
a. effects of waves at great distances
b. the ability of some waves to move very far
c. how displacements of interacting waves add together
d. relativistic wave behavior
[Ques. 8] A high-voltage power line 23.0 m above the ground carries a current of 2 200 A. What is the magnetic field due to the current directly underneath the power line? (0 = 4 107 Tm/A)
a. 19.1 T
b. 60.1 T
c. 60.9 mT
d. 12.0 mT
e. 12.0 T
[Ques. 9] A string is strung horizontally with a fixed tension. A wave of frequency 60.0 Hz is sent along the string, and it has a wave speed of 58.4 m/s. Then a second wave, one of frequency 120 Hz, is sent along the string. What is the wave speed of the second wave?
a. 29.2 m/s
b. 58.4 m/s
c. 117 m/s
d. 87.6 m/s
e. 234 m/s
[Ques. 10] An incredible amount of electrical energy passes down the funnel of a large tornado every second. Measurements at a distance of 12.8 km from a large tornado showed an almost constant magnetic field of 2.35 108 T associated with the tornado. What was the average current going down the funnel? (0 = 4 107 Tm/A)
a. 3.0E+3 A
b. 1.5E+3 A
c. 7.5E+2 A
d. 9.6E+2 A
e. 4.7E+3 A
Quick Reply
