This document contains 8 questions related to concepts in physics including: 1) Plank's quantum hypothesis and calculating frequency and wavelength from photon energy. 2) Calculating photon emission rate from a 100W lamp. 3) Calculating photon rate entering the eye at minimum intensity perception. 4) Experimental laws of blackbody radiation and proving Planck's formula satisfies them. 5) Calculating emissive power and wavelength of maximum emissive power for blackbodies at different temperatures. 6) Calculating temperature, emissive power, and total emissive power of the sun's surface using blackbody radiation. 7) Calculating characteristic wavelengths from absorption spectrum wavelengths of hydrogen gas. 8) Calculating

1. Sheet (1) 3 rd year Biomedical
Speed of light = 8
10x3 m/sec. Electron charge = 19
10x6.1 
coulomb
Planck’s constant = 6.62 x 34
10
jouls.sec
Stefan-Boltzmann constant = 5.67 x 8
10
W 42
Km 
1- State Blanck’s Quantum Hypothesis.
A  -ray photon emitted in a certain nuclear reaction has energy of 1 Mev.
Find its frequency and wavelength.
2- A 100 watt lamp emits light of average wavelength 596.7 nm. How many
photons per sec emit form it.
3- The minimum intensity that can be perceived by the eye is about 10
10
2
m/w . How many photons per second (at  =560 nm.) enter the pupil of the
eye at this intensity?. Consider the pupil area in this case = 0.5 2
cm .
4- Show the two experimental laws of the Black Body radiation, and then prove
that the Blanck’s formula for Black body radiation satisfy them.
5- What is the total emissive power per unit area and the wavelength at which
the monochromatic emissive power has its maximum value ( m ) for,
i- Tungsten lamp filament at 3000 o
C .
ii- Frying pan at 300 o
C .
iii-The human skin (T = 35 o
C ) Consider Black Body radiation in each case.
State the nature of the radiated m in each case.
6- The spectral study of the sun shows that the maximum intensity of the
emitted radiation occurs at m =500 nm. Assuming the sun to be a black
body,
i- Calculate the temperature of the surface of the sun.
ii- Find the emissive power per unit area of the sun’s surface.
iii- Find the total emissive power of the sun, if the radius of the sun is
4x 7
10 m.
7- Hydrogen like gas has ionization potential 54.4 volt is irradiated by an U.V.
beam of wavelength band 5.1602.24  nm. Find the corresponding
characteristic wavelengths of the absorption, emission and fluorescence
spectra and the energy levels of the gas. Show your answer by energy
level diagram.
8- The first series of the characteristic absorption spectrum of a certain gas are
30.44, 25.68,24.35 and 22.83 nm. Find the corresponding wavelengths of the
characteristic: i- Emission, ii- fluorescence spectra of this gas. Show your
answer by an energy level diagram.