The focal length of a concave mirror is 20 cm. What is its radius of curvature?
A) 10 cm
B) 40 cm
C) -40 cm
D) 20 cm
E) -20 cm
B
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The heliocentric model of the solar system was developed by
a. Brahe. b. Kepler. c. Copernicus. d. Newton.
Why is most matter electrically neutral?
a. It contains no charges. b. There are equal amounts of positive and negative charges present. c. The charge on the electrons and protons in the material is too small to notice. d. none of the above
Polarization: A beam of light is polarized in a vertical plane and has an intensity I0. The beam passes through an ideal polarizer and then through an ideal analyzer whose axis is set horizontally. If the axis of the polarizer is set at 60° with the vertical, what is the ratio of the intensity of the final beam to I0?
A. 0.19 B. 0.25 C. 0.31 D. 0.37 E. 0.43
A thin spherical copper shell of radius 9.5 cm carries an excess charge of -4.2 nC
How many excess electrons are on (a) the outer surface of the shell, and (b) the inner surface? (e = 1.60 × 10-19 C)