1
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
An object is placed at the focus of concave lens having focal length f. What is the magnification and distance of the image from the optical centre of the lens?
A
1, $$\infty$$
B
Very high, $$\infty$$
C
$${1 \over 2}$$, $${f \over 2}$$
D
$${1 \over 4}$$, $${f \over 4}$$
2
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Two plane mirrors M1 and M2 are at right angle to each other shown. A point source 'P' is placed at 'a' and '2a' meter away from M1 and M2 respectively. The shortest distance between the images thus formed is : (Take $$\sqrt 5$$ = 2.3)

A
3a
B
4.6a
C
2.3a
D
2$$\sqrt {10}$$a
3
JEE Main 2021 (Online) 27th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
Curved surfaces of a plano-convex lens of refractive index $$\mu$$1 and a plano-concave lens of refractive index $$\mu$$2 have equal radius of curvature as shown in figure. Find the ratio of radius of curvature to the focal length of the combined lenses.

A
$${1 \over {{\mu _2} - {\mu _1}}}$$
B
$${\mu _1} - {\mu _2}$$
C
$${1 \over {{\mu _1} - {\mu _2}}}$$
D
$${\mu _2} - {\mu _1}$$
4
JEE Main 2021 (Online) 27th August Morning Shift
MCQ (Single Correct Answer)
+4
-1
An object is placed beyond the centre of curvature C of the given concave mirror. If the distance of the object is d1 from C and the distance of the image formed is d2 from C, the radius of curvature of this mirror is :
A
$${{2{d_1}{d_2}} \over {{d_1} - {d_2}}}$$
B
$${{2{d_1}{d_2}} \over {{d_1} + {d_2}}}$$
C
$${{{d_1}{d_2}} \over {{d_1} + {d_2}}}$$
D
$${{{d_1}{d_2}} \over {{d_1} - {d_2}}}$$
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