Resistance and Resistivity: What is the resistance of a cylindrical metal rod 1.0 cm in diameter and 45 m long, if the resistivity of the metal is 1.4 × 10-8 ? ? m?
A. 0.0063 ?
B. 0.0080 ?
C. 0.80 ?
D. 6.3 ?
Answer: B
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In Gulliver's Travels, Jonathan Swift wrote about a country where astronomers had found that Mars had two moons. (The moons of Mars were unknown at that time)
"They have likewise discovered two lesser stars, or satellites, which revolve about Mars, whereof the innermost is distant from the center of the primary planet exactly three of his diameters, and the outermost five; the former revolves in the space of ten hours, and the latter in twenty-one and a half..." If this information were correct, what would the mass of Mars be? The radius of Mars is 3,393,500 m and G = 6.67 x 10-11 N•m2/kg2. A) 3.86 × 1024 kg B) 6.45 × 1023 kg C) 5.67 × 1021 kg D) 2.83 × 1021 kg E) 4.78 × 1020 kg
A guitar string is supposed to have a fundamental frequency 256 Hz. It currently has a fundamental frequency 248 Hz. What percentage increase in tension is required to bring the guitar string into tune?
A) 3.13% B) 6.56% C) 1.60% D) 6.15% E) 3.23%
Three resistors of 12 ?, 12 ?, and 6.0 ? are connected together, and an ideal 12-V battery is connected across the combination. What is the current through the battery if they are connected (a) in series or (b) in parallel?
What will be an ideal response?
When light passes from a material with a low index of refraction into material with a high index of refraction:
a. some light is reflected with a 180° change of phase. b. none of the light is reflected. c. some light is reflected without a change of phase. d. the light that is not reflected has a 180° change of phase.