Suppose you have a rock that, when it solidifies, contains 1 microgram of a radioactive isotope. How much of this isotope remains after five half-lives?
a. 1/32 microgram
b. none
c. 1/16 microgram
d. 1/8 microgram
e. Cannot be determined without knowing the daughter isotope.
Answer: a. 1/32 microgram
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One of the absorption lines of hydrogen has a rest wavelength of 656 nm (at rest means with respect to the observer, like in a lab). You observe several stars and measure the wavelength of this same hydrogen absorption line in each star
Based on the measured wavelength of this line, which star is moving towards the Earth the fastest? A) 670 nm B) 640 nm C) 656 nm D) 630 nm E) 680 nm
Consider a conducting bar that is free to slide along conducting rails in an upward magnetic field as shown in the diagram below. If we connect the rails to the battery shown, which way will the bar be pushed?
A.A
B.B
C.C
D.D
E. Down into the rails
F. Up off the rails
Secondary wavelets spread from a wave with
A) reduced speed. B) an unchanging speed. C) an increased speed. D) none of the above
In Young's two-slit experiment, a beam of light from a slit reaches at a point on the screen one wavelength behind the wave from the other slit. What is observed on the screen at that point?
A) Dark fringe B) An empty space C) Bright-dark fringe D) Dark-bright fringe E) Bright fringe