An unusual lightning strike has a vertical portion with a positive current of +400 A upwards. The Earth's magnetic field at that location is parallel to the ground and has a magnitude of 30 ?T. In N, the force exerted by the Earth's magnetic field on the 25-m-long current is
a. 0.
b. 0.012 N, East.
c. 0.012 N, West.
d. 0.30 N, West.
e. 300 N, East.
d
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A certain meteoroid [a rock in space] has been moving through our solar system ever since the solar system was formed, 5 billion years ago. Suppose the meteoroid is far from all planets and stars, so that the effect of gravity is negligible
Neglecting gravity, is any physical work being done on the meteoroid? A) No, because the force of inertia on the meteoroid is balanced by the equal reaction force by the meteroid. B) Yes, because work is always required to move any massive object through a distance. C) No, because no forces are exerted on the meteoroid. D) Yes, because the force of inertia is exerted on the meteoroid while the meteoroid moves. E) Yes, because the meteoroid is moving.
Light spreads out when it passes through a narrow slit because of
a. interference. b. diffraction. c. specular reflection. d. diffuse reflection. e. polarization.
An initially uncharged hollow metallic sphere with radius of 5 cm has a small object with a charge of -10 µC carefully placed at the center of the sphere through a hole in the latter's surface. What charge resides inner surface of the sphere?
a. -10 µC c. +10 µC b. zero d. -4000 µC
Semiconductor technology has been the basis for many new electronic devices
Indicate whether the statement is true or false