In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eye-piece forms a real image of this line. The length of this image is $$I$$. The magnification of the telescope is
A
$${{L + I} \over {L - I}}$$
B
$${L \over I}$$
C
$${L \over I} + 1$$
D
$${L \over I} - 1$$
2
AIPMT 2015
MCQ (Single Correct Answer)
+4
-1
A beam of light consisting of red, green and blue colours is incifent on a right angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47 respectively.
The prism will
A
not separate the three colours at all
B
separate the red colour part from the green and blue colours
C
separate the blue colour part from the red and green colours
D
separate all the three colours from one another
3
AIPMT 2015 Cancelled Paper
MCQ (Single Correct Answer)
+4
-1
The refracting angle of a prism is A, and refractive index of the material of the prism is cot (A/2). The angle of minimum deviation is
A
90o $$-$$ A
B
180o + 2A
C
180o $$-$$ 3A
D
180o $$-$$ 2A
4
AIPMT 2015 Cancelled Paper
MCQ (Single Correct Answer)
+4
-1
Two identical thin plano-convex glass lenses (refractive index 1.5) each having radius of curvature of 20 cm are placed with their convex surfaces in contact at the centre. The intervening space is filled with oil of refractive index 1.7. The focal length of the combination is
