A 60-W and a 100-W light bulb are rated at 120V. Which bulb has a higher resistance?
A) 60-W bulb
B) 100-W bulb
C) both the same.
Answer: A
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Jadeen says that you can increase the resistance of a copper wire by hammering the wire to make it narrower and longer. Arnell says that you can increase its resistance by heating the wire. Which one, if either, is correct, and why?
a. Arnell, because the conductivity of the wire increases when it is heated. b. Arnell, because the conductivity of the wire decreases when it is heated. c. Jadeen, because the conductivity of a wire is directly proportional to its area and inversely proportional to its length. d. Jadeen, because the conductivity of a copper wire does not increase when it is hammered. e. Both are correct because (b) and (d) are both correct.
Which of the following is true of ribonucleic acid (RNA)?
A) It carries the genetic code out of the nucleus. B) It remains safe in the nucleus of a cell. C) It is the building block of compounds such as proteins and carbohydrates. D) It is a long spiral molecule that stores the genetic code.
The flat rotation curves of spiral galaxies tell us that they contain a lot of dark matter. Do they tell us anything about where the dark matter is located within the galaxy?
A) Yes, they tell us that dark matter is spread throughout the galaxy, with most located at large distances from the galactic center. B) Yes, they tell us that dark matter is concentrated near the center of the galaxy. C) Yes, they tell us that dark matter is spread uniformly throughout the galactic disk. D) No, we cannot determine anything about the location of dark matter from the rotation curve.
Conservation of energy requires that if an atom absorbs a photon,
A. an electron ends up with an energy equal to that of the photon. B. the atom must emit a photon. C. an electron rises to a new orbital with an energy equal to that of the previous orbital plus the energy of the photon. D. the atom must emit an electron.