Which of the following statements about electromagnetic waves in free space are true?
A. The higher-frequency travel faster than the lower-frequency waves.
B. The higher-frequency waves have shorter wavelengths than the lower-frequency waves.
C. The wavelengths of the visible waves are some of the longest electromagnetic waves.
D. The wavelengths of the visible waves are some of the shortest electromagnetic waves.
E. The electric field vector is always at right angles to the magnetic field vector.
Answer:
B. The higher-frequency waves have shorter wavelengths than the lower-frequency waves.
E. The electric field vector is always at right angles to the magnetic field vector.
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A solenoid 4.0 cm in radius and 4.0 m in length has 8000 uniformly spaced turns and carries a current of 5.0 A. Consider a plane circular surface (radius = 2.0 cm) located at the center of the solenoid with its axis coincident with the axis of the solenoid. What is the magnetic flux through this surface? (1 Wb = 1 T ? m2)
A. 63 ?Wb B. 16 ?Wb C. 0.25 mWb D. 10 ?Wb E. 5.0 ?Wb
On a clear day, the sky appears to be more blue toward the zenith (overhead) than it does toward the horizon. This occurs because
A) the atmosphere is denser higher up than it is at the earth's surface. B) the temperature of the upper atmosphere is higher than it is at the earth's surface. C) the sunlight travels over a longer path at the horizon, resulting in more absorption. D) the atmosphere is more reddish over the ocean.
An electrical power plant manages to send 88% of the heat produced in the burning of fossil fuel into the water-to-steam conversion. Of the heat carried by the steam, 30% is converted to the mechanical energy of the spinning turbine. Which of the following choices best describes the overall efficiency of the heat-to-work conversion in the plant (as a percentage)?
a. greater than 88% c. 30% b. 64% d. less than 30%
Which of the following particles is made of two smaller particles?
a. electron c. photon b. proton d. None of these choices.