Drawing on Eratosthenes' method, if two observers are due north and south of each other and are separated by 400 km, what is the circumference of their spherical world if they see the same star on their meridian at altitudes of 23 degrees and 47
degrees respectively, and at the exact same time?
A) 2,000 km B) 4,000 km C) 6,000 km D) 8,000 km E) 12,000 km
C
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If the half-value layer for a particular energy gamma ray is 0.40 cm of lead. What fraction of a beam of these photons will penetrate 1.00 cm of lead?
A. 0.40 B. 0.18 C. 0.067 D. 0.60 E. 0.72
Thin Films: Two very flat glass plates, 16 cm long, are in contact at one end and separated by 0.020 mm at the other end. The space between the plates is occupied by oil with index of refraction 1.45. The refractive index of the glass plates is 1.55. The plates are illuminated at normal incidence with monochromatic light, and fringes are observed. If the spacing of the dark fringes is 2.0 mm, what is the wavelength of the monochromatic light?
A. 425 nm B. 475 nm C. 525 nm D. 675 nm E. 725 nm
In the Bohr model, the higher the value of n, the farther from the nucleus the electron is located. In the quantum model, the higher the value of n, the farther from the nucleus the electron ______________ is located
Fill in the blank(s) with correct word
A proton and electron, each travelling with the same velocity in the +x direction enter a region of uniform magnetic field in the +y direction. If the acceleration of the electron is a in the +z direction, what is the acceleration of the proton?
A. amp/me in the +z direction B. a in the +z direction C. ame/mp in the +z direction D. a in the –z direction E. amp/me in the -z direction F. ame/mp in the -z direction