1
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
A thin convex lens made from crown glass $$\left( {\mu = {3 \over 2}} \right)$$ has focal length $$f$$. When it is measured in two different liquids having refractive indices $${4 \over 3}$$ and $${5 \over 3},$$ it has the focal lengths $${f_1}$$ and $${f_2}$$ respectively. The correct relation between the focal lengths is :
A
$${f_1} = {f_2} < f$$
B
$${f_1} > f$$ and $${f_2}$$ becomes negative
C
$${f_2} > f$$ and $${f_1}$$ becomes negative
D
$${f_1}\,$$ and$${f_2}\,$$ both become negative
2
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
Two beams, $$A$$ and $$B$$, of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam $$A$$ has maximum intensity (and beam $$B$$ has zero intensity), a rotation of polaroid through $${30^ \circ }$$ makes the two beams appear equally bright. If the initial intensities of the two beams are $${{\rm I}_A}$$ and $${{\rm I}_B}$$ respectively, then $${{{{\rm I}_A}} \over {{{\rm I}_B}}}$$ equals:
A
$$3$$
B
$${3 \over 2}$$
C
$$1$$
D
$${1 \over 3}$$
3
JEE Main 2014 (Offline)
MCQ (Single Correct Answer)
+4
-1
A green light is incident from the water to the air - water interface at the critical angle $$\left( \theta \right)$$. Select the correct statement.
A
The entire spectrum of visible light will come out of the water at an angle of $${90^ \circ }$$ to the normal.
B
The spectrum of visible light whose frequency is less than that of green light will come out to the air medium.
C
The spectrum of visible light whose frequency is more than that of green light will come out to the air medium.
D
The entire spectrum of visible light will come out of the water at various angles to the normal.
4
JEE Main 2013 (Offline)
MCQ (Single Correct Answer)
+4
-1
A beam of unpolarised light of intensity $${{\rm I}_0}$$ is passed through a polaroid $$A$$ and then through another polaroid $$B$$ which is oriented so that its principal plane makes an angle of $${45^ \circ }$$ relative to that of $$A$$. The intensity of the emergent light is
A
$${{\rm I}_0}$$
B
$${{\rm I}_0}/2$$
C
$${{\rm I}_0}/4$$
D
$${{\rm I}_0}/8$$
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