A rock sample from the moon includes a mineral that contains small amounts of the radioactive isotope Potassium-40 and its daughter element Argon-40 (half-life of 1.3 billion years). This mineral would not form with any Argon-40
Consider a crystal with 7 atoms of Argon-40 for every 1 atom of Potassium-40. How many atoms of Potassium-40 were present when the crystal formed for each atom of Potassium-40 that exists today?
A) 1 B) 7 C) 8 D) None
C
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An effective theory must:
A) have been proven. B) must have been around for centuries or longer. C) be continuously tested. D) include mathematical formulae.
The Oort cloud was probably formed by planetesimals that were tossed to the outer parts of the Solar System by the planets.
Answer the following statement true (T) or false (F)
A photocathode having a work function of 2.8 eV is illuminated with monochromatic electromagnetic radiation whose photon energy is 4.0 eV
What is the threshold (cutoff) frequency for photoelectron production? (1 eV = 1.60 × 10-19 J, h = 6.626 × 10-34 J ? s) A) 6.8 × 1014 Hz B) 2.9 × 1014 Hz C) 7.7 × 1014 Hz D) 8.6 × 1014 Hz E) 9.7 × 1014 Hz
We find that N current loops are coplanar and coaxial. The first has radius a and current I. The second has radius 2a and current 2I, and the pattern is repeated up to the Nth, which has radius Na and current NI. The current in each loop is counterclockwise as seen from above. The magnitude of the magnetic field at the center of the loops is
A.
.B.
C.
.D.
.E.
.