Images of objects are formed by lenses because of
a. refraction.
b. diffraction.
c. internal reflection.
d. all of these.
a
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Plane Mirrors: A laser beam strikes a plane mirror's reflecting surface with an angle of incidence of 43°. What is the angle between the incident ray and the reflected ray?
A. 43° B. 86° C. 45° D. 90° E. 0°
Why do we think that quasars are extremely distant?
A. They are very bright. B. They are very faint. C. Their light varies rapidly. D. Their spectra show immense redshifts.
Assume that a certain city consumes electrical energy at an average rate of 2.0 × 109 W. What would be the mass change in producing enough energy to keep this city running for 21 weeks? (c = 3.00 × 108 m/s)
A) 0.28 kg B) 0.32 kg C) 0.39 kg D) 0.48 kg
The following three appliances are connected in parallel across an ideal 120-V dc power source: 1200-W toaster, 650-W coffee pot, and 600-W microwave. If all were operated at the same time what total current would they draw from the source?
A) 5.0 A B) 4.0 A C) 20 A D) 10 A