2.)The star nearest to Earth is Proxima Centauri, located at a distance of about
ID: 1479252 • Letter: 2
Question
2.)The star nearest to Earth is Proxima Centauri, located at a distance of about 4.2 light years. (a) If one could travel there at 99% of the speed of light (0.99c), what would be the apparent distance to the star? (b) If you traveled to Proxmia Centauri at this high velocity, stayed there for 2 years, and then returned (also at 0.99c), how much time would have passed on Earth?
3.) (a) What is the wavelength of light for the least energetic photon emitted in the Balmer series of the hydrogen atom spectrum lines? (b) What is the wavelength of the series limit?
4.) How many electron states are there in the following shells: (a) n = 4, (b) n = 1, (c) n = 3, (d) n = 2?
5.) A sample of a certain metal has a volume of 4.0E-3 m3. The metal has a density of 9.0 g/cm3 and a molar mass of 60 g/mol. The atoms are bivalent. How many conduction electrons (or valance electrons) are in the sample?
Explanation / Answer
Only 1 question at a time please
3)
a)E = 13.6 * [1/n1^2 - 1/n2^2]
for balmer series, n1 =2
For least energy n2=3
E = 13.6 * [1/n1^2 - 1/n2^2]
= 13.6 * [1/2^2 - 1/3^2]
= 1.89 eV
= (1.89*1.6*10^-19 ) J
=3.02*10^-19 J
lambda = h*C/E
= (6.626*10^-34)*(3*10^8) / (3.02*10^-19)
= 6.58*10^-7 m
Answer: 6.58*10^-7 m
b)
E = 13.6 * [1/n1^2 - 1/n2^2]
= 13.6 * [1/2^2 - 1/infinity]
= 13.6*1/4
= 3.4 eV
= (3.4*1.6*10^-19 ) J
=5.44*10^-19 J
lambda = h*C/E
= (6.626*10^-34)*(3*10^8) / (5.44*10^-19)
= 3.65*10^-7 m
Answer: 3.65*10^-7 m
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