A beam of 1-MeV gamma rays incident on a piece of 0.50-cm thick lead is reduced by 50% of its initial value. How thick must the lead be to reduce the beam to one percent of its initial value?
a. 1.1 cm
b. 2.2 cm
c. 3.3 cm
d. 4.4 cm
e. 8.4 cm
c
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When a bimetallic bar of copper and iron strips is heated, the bar bends toward the iron strip because
A) iron gets hotter before copper. B) copper gets hotter before iron. C) copper expands more than iron. D) iron expands more than copper. E) none of the above
The sky is dark at night:
A) because the stars in the Milky Way are far away. B) because the Sun is on the other side of Earth. C) because there are far fewer stars on the night side of Earth. D) because all the light from all the objects in the universe hasn't arrived here yet. E) because the quasars are too far away from Earth for their light to have arrived here.
The tallest volcano in the solar system is Mauna Kea, when measured from its base on the ocean floor to its highest point
Indicate whether the statement is true or false
Which method of extrasolar planet detection is able to measure the compositions of extrasolar planet atmopsheres?
A) gravitational lensing B) Doppler technique C) transit technique D) astrometric technique