If the current through a circuit of constant resistance is doubled, the power dissipated by that circuit will
A) quadruple in magnitude.
B) double in magnitude.
C) decrease to one-half of what it was.
D) decrease to one-fourth of what it was.
A
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The first of two identical boxes of mass m is sitting on level ground. The second box is sitting on a ramp that makes an angle with the ground. When a force of magnitude F is applied to each box in a direction parallel to the surface it is on, upwards on the box on the ramp, neither box moves. Which statement comparing the friction force on the box on the level, fL, to the friction force on the
box on the ramp, fR, is correct? a. fR = fL b. fR > fL c. fR < fL d. The coefficient of static friction is needed to determine the correct answer. e. Depending on the values of the coefficient of static friction, the angle of elevation of the ramp, the mass of the boxes, and the applied force, answers (a), (b), and (c) are each a possible correct answer.
The pulsation in the luminosity of variable stars is driven by the changing opacity of their atmosphere.
Answer the following statement true (T) or false (F)
A concave mirror has a focal length of 20 cm. What is the magnification if the object's distance is 100 cm?
a. 1/2 b. 1/4 c. -2 d. 4 e. -1/4
Suppose you point your telescope at a distant object. Which of the following is not an advantage of taking a photograph of the object through the telescope as compared to just looking at the object through the telescope?
A) The photograph will have far better angular resolution than you can see with your eye. B) By using a long exposure time, the photograph can allow you to see objects that would be too dim to see with your eye. C) If taken with a camera with a sensitive detector such as a CCD, the photograph can capture a much larger percentage of the incoming photons than can your eye. D) The photograph provides a more reliable record of what is seen through the telescope than can a drawing made by eye.