Let "m" represent the mass of an electron, and "c" represent the speed of light. In order to create an electron-positron pair, we must start with a photon whose energy is
A) at least mc2.
B) at least 2mc2.
C) at least 4mc2.
D) any value greater than zero.
E) Actually it is impossible to create such pairs from photons.
B
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Why did Galileo's observations of moons orbiting Jupiter disagree with geocentric model of the universe of his time?
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The position of a mass that is oscillating on a spring is given by x = (12.3 cm) cos[(1.26 s-1)t]. What is the speed of the mass when t = 0.805 s?
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Two concentric conducting spheres of radii a = 5 cm and b = 10 cm have a potential difference V = 100 V between them. What is the charge carried by each sphere?
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