In photoelectric emission, the work function is the minimum
A) frequency of light to produce emission.
B) energy required to eject an electron from the surface.
C) energy an emitted electron possesses.
D) none of the above
Answer: B
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The season is winter in the northern hemisphere. The Sun rises high in the sky for those living in the southern hemisphere
a. True b. False Indicate whether the statement is true or false
Applications to Astronomy: The earth's orbit has a mean radius of 1.5 × 108 km. Over a six-month period, the apparent position of a particular star varies by 0.00014° due to parallax. How many light-years is this star from Earth? (1 ly = 9.46 × 1015 m)
A. 0.13 ly B. 1.3 ly C. 13 ly D. 130 ly
A ball of mass 5.0 kg is suspended by two wires from a horizontal arm that is attached to a vertical shaft, as shown in the figure
The shaft is in uniform rotation about its axis. The rate of rotation is adjusted until the tensions in the two wires are EQUAL. At that speed, the radial acceleration of the ball is closest to A) 4.9 m/s2. B) 5.9 m/s2. C) 6.9 m/s2. D) 7.9 m/s2. E) 9.9 m/s2.
What makes us think that the star system Cygnus X-1 contains a black hole?
A) It emits x-rays as we expect from a system with an accretion disk, but the unseen star in the system is too massive to be a neutron star. B) No light is emitted from this star system, so it must contain a black hole. C) The fact that we see strong x-ray emission tells us that the system must contain a black hole. D) Cygnus X-1 is a powerful x-ray burster, so it must contain a black hole.