How many atoms are present in a sample of pure iron with a mass of 210 g? (The atomic mass of iron = 56 u and NA = 6.02 × 10^23.)
a. 1.8 × 10^19
c. 2.3 × 10^24
b. 2.3 × 10^28
d. 3.2 × 10^28
C
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When light enters a denser medium, the speed of the light ______________
Fill in the blank(s) with correct word
A flat circular coil having 57 turns of very thin wire has a diameter of 9.5 cm and carries 7.2 A of current. (?0 = 4? × 10-7 T ? m/
A) (a) What is the strength of the magnetic field at the center of the coil? (b) If the same length of wire were used to make a coil with twice the original diameter, how large would the magnetic field at the center be when it carried the same current as before?
The combination of two separated point charges of opposite sign but equal magnitude is called an electric:
a. monopole. b. dipole. c. quadrapole. d. magnapole.
In a double-slit experiment, the distance between the slits is 0.2 mm, and the distance to the screen is 150 cm. What wavelength (in nm) is needed to have the intensity at a point 1 mm from the central maximum on the screen be 80% of the maximum intensity?
a. 900 b. 700 c. 500 d. 300 e. 600