1.what is polaroid?hoe are they constructed ? mention their important application?
2.state law of malus and draw an intensity v/s angle between the plane of transmission of polarizer and analyzer?
3.state brewsters law and prove that the reflected and refracted rays are mutually perpendicular at the angle of polarization?

Asked by mahamood.iphone | 22nd Dec, 2015, 12:35: PM

Expert Answer:

3. Brewsters law:
According to this law, when unpolarized light is incident at polarizing angle, ip on an interface separating air from a medium of refractive index μ, then the reflected light is fully polarized (perpendicular to the plane of incidence), provided μ = tan ip. This relation represents Brewster's law.
It has been observed experimentally that when light is incident at polarizing angle, the reflected component along OB and refracted component along OC are mutually perpendicular to each other.
Thus, in fig.,

begin mathsize 14px style angle BOY plus angle YOC equals 90 degree left parenthesis 90 degree minus straight i subscript straight p right parenthesis plus left parenthesis 90 degree minus straight r right parenthesis equals 90 degree end style
where, r is the angle of refraction.
or
90º - ip = r

According to Snell's law, 
begin mathsize 14px style straight mu equals fraction numerator sin space straight i over denominator sin space straight r end fraction When space space straight i equals straight i subscript straight p comma space straight r equals left parenthesis 90 degree minus straight i subscript straight p right parenthesis therefore straight mu equals fraction numerator sin space straight i subscript straight p over denominator sin space left parenthesis 90 degree minus straight i subscript straight p right parenthesis end fraction straight mu equals fraction numerator sin space straight i subscript straight p over denominator cos space straight r subscript straight p end fraction equals tan space straight i subscript straight p end style
This proves Brewster's law.
 
We can prove that in case of refletion at Brewster's angle, reflected and refracted rays are mutually perpendicular.
According to Brewster's law,
Syntax error from line 1 column 49 to line 1 column 90. Unexpected 'mathvariant'.
According to Snell's law,
Syntax error from line 1 column 49 to line 1 column 90. Unexpected 'mathvariant'.
sin r = cos ip = sin (90º - ip)
r = 90º - ip   or   ip + r = 90º

In fig,
 
r' = ip
begin mathsize 14px style therefore end styler' + r = 90º
begin mathsize 14px style left square bracket 90 º minus angle BOY right square bracket plus left parenthesis 90 degree minus angle COY right parenthesis equals 90 degree angle BOY plus angle COY equals 90 degree therefore angle BOC equals 90 degree straight i. straight e. comma space the space angle space between space reflected space rays space left parenthesis along space OB right parenthesis space and space refracted space rays space left parenthesis along space OC right parenthesis space is space 90 degree. end style
 
Note: Ask the other questions as a separate separate query.

Answered by Faiza Lambe | 22nd Dec, 2015, 03:48: PM