Which of the following terms describe lenses that are thinner at the center than at the edges? (There could be more than one correct choice.)
A) convex lenses B) diverging lenses C) converging lenses D) concave lenses
B, D
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Calculate: (a) time elapsed in cooling the surface of the sphere to 204°C and (b) time elapsed in cooling the center of the sphere to 204°C.
A steel sphere with a diameter of 7.6 cm is to be hardened by first heating it to a uniform
temperature of 870°C and then quenching it in a large bath of water at a temperature of 38°C.
The following data apply
GIVEN
FIND
(a) Time elapsed in cooling the surface of the sphere to 204°C
(b) Time elapsed in cooling the center of the sphere to 204°C
ASSUMPTIONS
Constant water bath temperature, thermal properties, and transfer coefficient
SKETCH
Radiative energy is
A) energy carried by light. B) heat energy. C) energy from nuclear power plants. D) energy of motion.
Adiabatic processes occur in Earth's
A) atmosphere. B) oceans. C) mantle. D) all of the above E) none of the above
If body P, with a positive charge, is placed in contact with body Q (initially uncharged), what will be the nature of the charge left on Q?
a. must be equal in magnitude to that on P b. must be negative c. must be positive d. must be greater in magnitude than that on P