What's an isotope?
a. a radioactive material
b. an atom of an element with a different number of neutrons in the nucleus
c. an electrically charged atom
d. none of the above
b
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Why should photons emitted by a hotter gas have, on average, shorter wavelengths than photons emitted by a cooler gas?
What will be an ideal response?
Spherical Mirrors: When a person stands 40 cm in front of a cosmetic (concave) spherical mirror, the upright image is twice the size of the object. What is the focal length of the mirror?
A. 27 cm B. 40 cm C. 80 cm D. 160 cm
What is the power of a lens that has a focal length of -40 cm?
A) -2.5 diopters B) -4.0 diopters C) +4.0 diopters D) +2.5 diopters E) +2.7 diopters
Three flat layers of transparent material are stacked upon one another. The top layer has index of refraction n1, the middle has n2 and the bottom one has n3 . If n1 < n2 < n3, at what angle of incidence will a ray of light traverse the three layers in a single straight line?
a. ?i = sin–1(1/n1) b. ?i = sin–1(1/(n1+n2+n3) c. ?i = tan–1(1/(n1+n2+n3) d. There is such an angle, but it is not given.