The magnitude of the magnetic field that a long and extremely thin current-carrying wire produces at a distance of 3.0 µm from the center of the wire is 2.0 × 10-3 T. How much current is flowing through the wire? (?0 = 4? × 10-7 T ? m/A)
A) 380 mA B) 190 mA C) 30 mA D) 19 mA
C
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Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case
A) Galaxy 1 must be twice as big as Galaxy 2. B) we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2. C) we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2. D) Galaxy 2 must be twice as old as Galaxy 1.
The first scientist to be credited for postulating that Earth circled the Sun was
A) Aristotle. B) Copernicus. C) Galileo. D) Newton.
During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?
A) Earth and Mars are getting closer together. B) Mars is moving around the Sun in the opposite direction from which Earth is moving around the Sun. C) Earth is catching up with and passing by Mars in their respective orbits. D) Earth and Mars are on opposite sides of the Sun.
Which of the following did the planetary model of the atom fail to explain?
A. the relationship between orbital radius and energy B. why alpha particles in Rutherford’s experiment deflected at high angles when incident on atomic foils C. why most alpha particles in Rutherford’s experiment passed with little deflection through atomic foils D. why electrons in atoms don’t radiate all their energy away rapidly