Biology Forums - Study Force

A spherical interplanetary grain of dust of radius 0.2 mm is at a distance r1 from the Sun. The gravitational force exerted by the Sun on the grain just balances the force due to radiation pressure from the Suns light. Assume the grain is moved to a distance 2r1 from the Sun and released. At this location, what is the net force exerted on the grain?
  1.toward the Sun
  2.away from the Sun
  3.zero
  4.impossible to determine without knowing the mass of the grain

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[Ques. 2] Assume the amplitude of the electric field in a plane electromagnetic wave is E1 and the amplitude of the magnetic field is B1. The source of the wave is then adjusted so that the amplitude of the electric field doubles to become 2E1. What happens to the intensity of the wave?
  1.It becomes four times larger.
  2.It becomes two times larger.
  3.It can stay constant.
  4.It becomes one-half as large.
  5.It becomes one-fourth as large.

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[Ques. 3] A small source radiates an electromagnetic wave with a single frequency into vacuum, equally in all directions. As the wave moves, the amplitude of its electric field:
  1.increases.
  2.decreases.
  3.stays constant.

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[Ques. 4] A small source radiates an electromagnetic wave with a single frequency into vacuum, equally in all directions. As the wave moves, its intensity:
  1.increases.
  2.decreases.
  3.stays constant.

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[Ques. 5] A small source radiates an electromagnetic wave with a single frequency into vacuum, equally in all directions. As the wave moves, its speed:
  1.increases.
  2.decreases.
  3.stays constant.

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[Ques. 6] A small source radiates an electromagnetic wave with a single frequency into vacuum, equally in all directions. As the wave moves, its wavelength:
  1.increases.
  2.decreases.
  3.stays constant.

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[Ques. 7] A small source radiates an electromagnetic wave with a single frequency into vacuum, equally in all directions. As the wave moves, its frequency:
  1.increases.
  2.decreases.
  3.stays constant.

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[Ques. 8] Assume you charge a comb by running it through your hair and then hold the comb next to a bar magnet. Do the electric and magnetic fields produced constitute an electromagnetic wave?
  1.Yes they do, necessarily.
  2.Yes they do, because charged particles are moving inside the bar magnet.
  3.They can, but only if the electric field of the comb and the magnetic field of the magnet are perpendicular.
  4.They can, but only if both the comb and the magnet are moving.
  5.They can, if either the comb or the magnet or both are accelerating.

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[Ques. 9] A student working with a transmitting apparatus like Heinrich Hertzs wishes to adjust the electrodes to generate electromagnetic waves with a frequency half as large as before. After she makes the required adjustment, what will the wavelength of the transmitted wave be?
  1.four times larger than before
  2.two times larger than before
  3.one-half as large as before
  4.one-fourth as large as before
  5.none of those answers

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[Ques. 10] A student working with a transmitting apparatus like Heinrich Hertzs wishes to adjust the electrodes to generate electromagnetic waves with a frequency half as large as before. How large should she make the effective capacitance of the pair of electrodes?
  1.four times larger than before
  2.two times larger than before
  3.one-half as large as before
  4.one-fourth as large as before
  5.none of those answers

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