1a) In terms of wavelength, frequency and energy compare the two photons with wa
ID: 1057707 • Letter: 1
Question
1a) In terms of wavelength, frequency and energy compare the two photons with wavelengths of 900 nm and 780 nm.
b) What are the emission spectra of an element?
c) How are the emission spectra of an element produced?
d) How did Bohr (quantum theory) explain the emission (line) spectra of hydrogen?
2.a) A laser used to dazzle the audience in a rock concert emits green light with a wavelength() of 515 nm. Calculate the frequency of the light. (v=c/; c=3.00x108m/s; 1nm=10-9m)
Show set-up and give answers with the correct number of significant figures.
b) Green light has a frequency of about 6.00x1014 s-1. What is the energy of green light? (h=6.626x10-34 Js).
Explanation / Answer
Ans.1
A) Photon 1 : wavelength -=900 nm = 9 X 10-7 m
frequency is speed of light divided by wavelenth i.e v=c/
frequncy = 3x108m/9x10-7m = 3.33 x 1014 Hertz
energy = plank's constant x frequency
=6.626 x10-34 x 3.33 x 1014 Hertz = 2.206 x 10-19 J
Photon 2 : wavelength = 780 nm = 7.8 X 10-7 m
frequency is speed of light divided by wavelenth i.e v=c/
frequency = 3x108m/7.8x10-7m = 3.846 x 1014 hertz
energy = plank's constant x frequency =6.626 x10-34 x 3.846 x 1014 hertz = 2.548 x 10-19 J
Hence , wavelength : Photon 1 > Photon 2
frequency : Photon 2 > Photon 1
energy : Photon 2 > Photon 1
B) When an element is heated up or gets energy it emitts radiation in electromagnetic waves. The spectrum of these waves as per its wavelenth series is known as emission spectra of an element.
C) Emission spectra are produced when electron from higher states (excited state ) falls to a lower state.
D) Bohr explained the electron changing its state from higher to lower states. When it fall to n=1 it emitts different emission known as lyman series and when it falls to n=2 it is known as barmer series.
As per Chegg policy only first question should be answered.
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