An open circuit consists of a 12-F parallel plate capacitor ...

[clippers!]

An open circuit consists of a 12-F parallel plate capacitor charged to 200 V and a 10- resistor. At the instant when a switch closes the circuit (with no battery in it) the displacement current between the plates of the capacitor is
 a. 1.2 A.
  b. 2.4  104 A.
  c. 2.4 mA.
  d. 10 A.
  e. 20 A.

Question 2

You can raise the temperature of an object with
 a. microwaves.
  b. infrared waves.
  c. ultraviolet rays.
  d. all of the above.
  e. only (a) and (b) above.

Question 3

At every instant the ratio of the magnitude of the electric to the magnetic field in an electromagnetic wave in vacuum is equal to
 a. the speed of radio waves.
  b. the speed of light.
  c. the speed of gamma rays.
  d. all of the above.
  e. only (a) and (b) above.

Question 4

Magnetic fields are produced by
 a. constant electric currents.
  b. electric currents that vary sinusoidally with time.
  c. time-varying electric fields.
  d. all of the above.
  e. only (a) and (b) above.

Question 5

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.

Question 6

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.

Question 7

In the atmosphere, the shortest wavelength electromagnetic waves are called
 a. microwaves.
  b. infrared waves.
  c. ultraviolet waves.
  d. X-rays.
  e. gamma rays.

Question 8

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

Question 9

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.

Question 10

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

Question 11

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

Question 12

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

Question 13

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

Question 14

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

Question 15

What is the maximum radiation pressure exerted by sunlight in space (S = 1350 W/m2) on a highly polished silver surface?
 a. 1.4  102 Pa
  b. 0.12 Pa
  c. 9.0  106 Pa
  d. 4.5  105 Pa
  e. 2.3  106 Pa

Question 16

What is the maximum radiation pressure exerted by sunlight in space (S = 1350 W/m2) on a flat black surface?
 a. 2.25  105 Pa
  b. 0.06 Pa
  c. 7  104 Pa
  d. 4.5  106 Pa
  e. 9.0  106 Pa

Question 17

At a distance of 10 km from a radio transmitter, the amplitude of the E field is 0.20 volts/meter. What is the total power emitted by the radio transmitter?
 a. 10 kW
  b. 67 kW
  c. 140 kW
  d. 245 kW
  e. 21 kW

Question 18

How much electromagnetic energy is contained in each cubic meter near the Earth's surface if the intensity of sunlight under clear skies is 1000 W/m2?
 a. 3.3  106 J
  b. 3.3 J
  c. 0.003 J
  d. 104 J
  e. 3.0  105 J

Question 19

A 100-kW radio station emits EM waves in all directions from an antenna on top of a mountain. What is the intensity of the signal at a distance of 10 km?
 a. 8  105 W/m2
  b. 8  106 W/m2
  c. 3  103 W/m2
  d. 0.8 W/m2
  e. 2.5  105 W/m2

Question 20

What is the average value of the magnitude of the Poynting vector at 1 meter from a 100-watt lightbulb radiating in all directions?
 a. 1 W/m2
  b. 4 W/m2
  c. 2 W/m2
  d. 8 W/m2
  e. 12 W/m2

Question 21

Find the force exerted by reflecting sunlight off a reflecting aluminum sheet in space if the area normal to the sunlight is 10,000 m2 and the solar intensity is 1350 W/m2.
 a. 0.72 N
  b. 0.09 N
  c. 9 N
  d. 45 N
  e. 0.18 N

Question 22

If the maximum E-component of an electromagnetic wave is 600 V/m, what is the maximum B-component?
 a. 1.4 T
  b. 1.8  105 T
  c. 2.0  106 T
  d. 1.0  103 T
  e. 1.6  1010 T

Question 23

If the radiant energy from the Sun comes in as a plane EM wave of intensity 1340 W/m2, calculate the peak values of E and B.
 a. 300 V/m, 104 T
  b. 1000 V/m, 3.35  106 T
  c. 225 V/m, 1.60 103 T
  d. 111 V/m, 3.00  105 T
  e. 711 V/m, 2.37  106 T

Question 24

The Earth is 1.49  1011 meters from the Sun. If the solar radiation at the top of the Earth's atmosphere is 1340 W/m2, what is the total power output of the Sun?
 a. 7.10  1027 W
  b. 2.20  1030 W
  c. 6.62  1026 W
  d. 3.74  1026 W
  e. 2.98  1025 W

Question 25

An ac power generator produces 50 A (rms) at 3600 V. The voltage is stepped up to 100,000 V by an ideal transformer and the energy is transmitted through a long distance power line which has a resistance of 100 ohms. What percentage of the power delivered by the generator is dissipated as heat in the long-distance power line?

[dominiqueenicolee]

Answer to Question 1

e

Answer to Question 2

d

Answer to Question 3

d

Answer to Question 4

d

Answer to Question 5

c

Answer to Question 6

a

Answer to Question 7

e

Answer to Question 8

a

Answer to Question 9

d

Answer to Question 10

a

Answer to Question 11

d

Answer to Question 12

c

Answer to Question 13

a

Answer to Question 14

a

Answer to Question 15

c

Answer to Question 16

d

Answer to Question 17

b

Answer to Question 18

a

Answer to Question 19

a

Answer to Question 20

d

Answer to Question 21

b

Answer to Question 22

c

Answer to Question 23

b

Answer to Question 24

d

Answer to Question 25

0.18

[clippers!]

Both answers were spot on, thank you once again

[dominiqueenicolee]

Great! Please up vote