The half-life of 131I is 8.04 days. Three days after it was prepared, its activity was 0.50 ?Ci. How many curies (in ?Ci) were initially prepared?
a. .60
b. .70
c. .65
d. .55
e. .39
c
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Which of the following statements are correct? (There could be more than one correct choice.)
A) Spherical aberration, but not chromatic aberration, occurs for lenses. B) Chromatic aberration, but not spherical aberration, occurs for lenses. C) Both chromatic aberration and spherical aberration occur for lenses. D) Both chromatic aberration and spherical aberration occur for spherical mirrors.
A Sun-like star will experience a helium flash in the core if
a. it is less massive than about 3 solar masses. b. it has become a red giant star. c. it has formed a helium core. d. the material in the core has gradually become degenerate. e. All of the other choices are correct.
Graphical Analysis: The figure shows a graph of the velocity of an object as a function of time. What is the acceleration of the object at the following times?(a) At 1.0 s(b) At 3.0 s
What will be an ideal response?
A series circuit consists of a 0.55-H inductor with internal resistance of 8.0 ? connected in series with a 4.0-? resistor, an open switch, and an ideal 12-V battery
(a) When the switch is closed, what is the initial current through the 4.0-? resistor? (b) What is the current through the 4.0-? resistor a very long time after the switch is closed?