Two identical silver spheres of mass m and radius r are placed a distance R (sphere 1) and 2R (sphere 2) from the Sun, respectively. The ratio of the gravitational force exerted by the Sun on sphere 1 to the pressure of solar radiation on sphere 1 is T1; the ratio for sphere 2 is T2 . The ratio of T2 to T1 is
a. 0.25.
b. 0.50.
c. 1.0.
d. 2.0.
e. 4.0.
[Ques. 2] Two identical silver spheres of mass m and radius r are placed a distance R (sphere 1) and 2R (sphere 2) from the Sun, respectively. The ratio of the pressure of solar radiation on sphere 2 to that on sphere 1 is
a. 0.25.
b. 0.50.
c. 1.0.
d. 2.0.
e. 4.0.
[Ques. 3] In the atmosphere, the shortest wavelength electromagnetic waves are called
a. microwaves.
b. infrared waves.
c. ultraviolet waves.
d. X-rays.
e. gamma rays.
[Ques. 4] The intensity of radiation reaching the Earth from the Sun is 1350 W/m2 . The Earth's radius is 6.4 106 m. How big a force does this radiation exert on the Earth? (Assume it is all absorbed.)
a. 5.8 108 N
b. 1.2 109 N
c. 2.3 109 N
d. 4.6 109 N
e. 1.7 1017 N
[Ques. 5] High frequency alternating current is passed through a solenoid that contains a solid copper core insulated from the coils of the solenoid. Which statement is correct?
a. A copper core remains cool no matter what the frequency of the current in the solenoid is.
b. The copper core remains cool because the induced emf is parallel to the solenoid axis and fluctuates rapidly.
c. The copper core heats up because an emf parallel to the solenoid axis is induced in the core.
d. The copper core heats up because circular currents around its axis are induced in the core.
e. The copper core heats up because the electric field induced in the copper is parallel to the magnetic field produced by the solenoid.
[Ques. 6] A solar cell has a light-gathering area of 10 cm2 and produces 0.2 A at 0.8 V (DC) when illuminated with S = 1000 W/m2 sunlight. What is the efficiency of the solar cell?
a. 16
b. 7
c. 23
d. 4
e. 32
[Ques. 7] What should be the height of a dipole antenna (of dimensions 1/4 wavelength) if it is to transmit 1200 kHz radiowaves?
a. 11.4 m
b. 60 cm
c. 1.12 m
d. 62.5 m
e. 250 m
[Ques. 8] An FM radio station broadcasts at 98.6 MHz. What is the wavelength of the radiowaves?
a. 60.8 m
b. 6.08 m
c. 3.04 m
d. 0.314 m
e. 0.33 cm
[Ques. 9] Green light has a wavelength of 5.4 107 m. What is the frequency of this EM-wave in air?
a. 5.56 1014 Hz
b. 6.00 1011 Hz
c. 9.00 108 Hz
d. 3.00 1010 MHz
e. 1.80 1015 Hz
[Ques. 10] Find the frequency of X-rays of wavelength 1 = 1010 m.
a. 3 1018 Hz
b. 3 1010 MHz
c. 6 109 Hz
d. 3 108 Hz
e. 3 1020 Hz
Quick Reply
