A roentgen (R) is
A) 10-2 J/kg.
B) 3.70 × 1010 decays/s in radium.
C) the SI unit of radioactivity ( = 1 decay/s).
D) the SI unit of absorbed dose = 1 J/kg = 100 rad.
E) a dosage of 2.58 × 10-4 C/kg.
E
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A light source radiates 60.0 W of single-wavelength sinusoidal light uniformly in all directions
What is the amplitude of the electric field of this light at a distance of 0.400 m from the bulb? (?0 = 8.85 × 10-12 C2/N ? m2, ?0 = 4? × 10-7 T ? m/A, c = 3.00 × 108 m/s) A) 162 N/C B) 212 N/C C) 82.1 N/C D) 150 N/C E) 52.9 N/C
The force of gravity is the only one of the four forces felt on very large size scales. Which of the following best explains why the other forces don't play a major role on large scales?
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In the context of the Doppler effect, which of the following is a difference between a blueshift and a redshift?
A) Unlike a redshift, a blueshift is caused by a velocity of recession. B) Unlike a blueshift, a redshift is based on the Hubble's law. C) Unlike a redshift, a blueshift is a shift toward shorter wavelengths. D) Unlike a blueshift, a redshift is based on a light source moving closer to an object.
Total Internal Reflection: A light beam with wavelength 440 nm in a certain material then enters air and its wavelength becomes 577 nm.(a) What is the index of refraction for the material?(b) At what angle with the plane of the surface will the light be totally reflected back into the material?
Fill in the blank(s) with the appropriate word(s).