Blue light (l = 460 nm) is incident on a piece of potassium (W = 2.45 eV). What is the maximum kinetic energy of the ejected photoelectrons? (h = 6.63 × 10^-34 J×s, c = 3.00 × 10^8 m/s, 1 eV = 1.60 × 10^-19 J, and 1 nm = 10-9 m)

a. 1.0 eV
c. 0.50 eV
b. 0.25 eV
d. 4.9 eV


B

Physics & Space Science

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A horizontally-projected beam of electrons travelling at 55 km/s travels between two parallel plates separated by 7.4 cm, and 12 cm long, between which there is an electric field of 7.2 mV/m upward. If the beam enters the region at a height of 3.7 cm above the lower plate, at what height above the lower plate is the beam when it exits? The electron mass is

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A planet is much brighter than the star it orbits

a. True b. False Indicate whether the statement is true or false

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A 4.7-kg solid sphere, made of metal whose density is 4000 kg/ , hangs by a light cord. When the sphere is immersed in water, what is the tension force the cord exerts on the sphere? The density of water is 1000 kg/m3

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