Download MCAT MODERN PHYSICS

IMPORTANT KEY POINTS OF MCAT PHYSICS
1:-When fast moving electron deeply penetrate into atoms passes near the nucleus
then they gives continuous X-rays.
2:-Intensity of emitted x-rays can be increased by increasing the current in the
filament.
3:- X-rays are produces by inner shell transition of electron from heavy element not
by lighter element.
4:- Quality of X-rays depends upon accelerating voltage & material of target specimen.
5:-Rest mass of X-ray photon is zero. & have no charge.
6:-Reverse of X-ray production is photo electric effect.
7:-X-rays of lower penetration power are soft X-rays & have low frequency & energy.
8:-X-rays if higher penetration power are hard X-rays & have higher frequency &
energy.
9:-In electromagnetic spectrum X-ray region is situated b/w gamma rays & ultraviolet
ray region.
10:-Penetration power of X-ray photons can be increased by increase in intensity or
frequency.
11:-Wavelength of continous X-rays depends upon intensity of incident electrons.
12:-X-rays are electromagnetic in nature & discovered by Reontgen.
13:-Modern tube to produce X-rays is designed by Dr. William Coolidge.
14:-The energy of X-ray photon is enough to produce photo electric effect & Compton
effect but not enough to produce pair production.
15:-Water is circulated in the X-ray tube to cool the target element.
16:-Maximum velocity of X-ray photon is given by,
V =  2hfmax /m
or  2Ve/m
UNIT:-MODERN PHYSICS
19:- First laser was discovered by C.H TOWNES.
20:-First liquid laser was built by PETER SOROKINS.
21:- In He-Ne laser He acts as pumping medium & Ne acts as Lasing or active medium.
22:- Wavelength of X-rays is of the order of 1 Ao =0.1 nm = 10-8 cm = 10-7 mm = 10-4  m =100 pm
23:- Optical pumping is process to produce population inversion.
24:-Wave length of electromagnetic spectrum is given below,
S.No.
1
2
3
4
(m)
Type Of E.M.R
S.No.
Type Of E.M.R
(m)
5
6
7
8
Ultra-violet rays
X-rays
Gamma rays
10-8
10-10
10-12
3
Radio Waves
Micro Waves
Infrared Waves
Visible light Wave
10
10-2
10-5
10-6
25:- Diffraction of X-rays with crystal was first studied by Laue & also by W.H Bragg’s &
W.L Bragg’s.
26:- Frequency of electromagnetic spectrum is given below,
S.No.
1
2
3
4
Type Of E.M.R
Radio Waves
Micro Waves
Infrared Waves
Visible light Wave
f (Hz)
4
10
108
1012
1015
S.No.
5
6
7
8
Type Of E.M.R
Ultra-violet rays
X-rays
Gamma rays
f (Hz)
1015 1016
1018
1020
27:- X-rays are not deflected by magnetic & electric fields as they have no charge.
28:- The wavelength of X-rays is given by,  =
𝒉𝒄
𝑽𝒆
𝑽𝒆
17:-The difference b/w soft & hard X-rays is of frequency.
29:- The frequency of X-rays is given by, f =
18:-Penetration power of X-rays photon does not depends upon current in the filament
30:- Energy of K
depends upon energy, wavelength & applied voltage.
31:- Speed of electromagnetic wave is given by, C = 1/  µ00
𝒉
X rays is – 10.2 eV. & that of K X-rays is -12.09 eV.
BY:- YASIR MUKHTAR……………………………………………………<STUDENT OF MCAT>………………………………………………………… Page 1
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