An object is placed at an unknown distance from a convex objective lens of focal length 5 cm . The objective lens forms a real image which acts as an object for a convex eyepiece of focal length 6.25 cm . The distance between the objective and eyepiece is 20 cm . The microscope is adjusted so that the final image is formed at the least distance of distinct vision $(25 \mathrm{~cm})$. Which of the following is correct?
A. Object distance $=7.5 \mathrm{~cm}$; Total magnification $=10$
B. Object distance = 10 cm ; Total magnification = 20
C. Object distance $=5 \mathrm{~cm}$; Total magnification $=20$
D. Object distance = 2.5 cm ; Total magnification = 10
C
D
B
A
From the same point, two stones A and B are thrown simultaneously, A is thrown up vertically with a velocity of $10 \mathrm{~ms}^{-1}$ and $B$ is thrown up with the same velocity at $30^{\circ}$ with the horizontal. The separation between the balls at 2 s is
25 m
10.5 m
22 m
20 m
If a clear liquid has a refractive index of 1.45 and a transparent solid has a refractive index of 2.9 , then for total internal reflection to occur at the interface between the two media; which of the following is correct?
A. The ray must travel from transparent solid to liquid at an angle of $15^{\circ}$
B. The ray must travel from liquid to transparent solid at an angle of $45^{\circ}$
C. The ray must travel from transparent solid to liquid at an angle of $30^{\circ}$
D. The ray must travel from liquid to transparent solid at an angle of $60^{\circ}$
B
C
D
A
Two deuterons are fused to form one alpha particle. If binding energy per nucleon of deuterium is 1.05 MeV and that of alpha particle is 7 MeV , what is the energy released in the formation of one alpha particle from the fusing of two deuterons?
24.8 MeV
23.8 MeV
26.8 MeV
28.3 MeV
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