Physics - Mock Test 38

Question 371

A convex lens of focal length f1 and a concave lens of focal length f2 are placed in contact. The focal length of the combination is?

A) f2 + f1 B) f2 - f1 C) f1f2/f2+f1 D) f1f2/f1-f2

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Question 372

Two convex lenses of equal focal length f are placed in contact the resultant focal length of the combination is?

A) zero B) focus C) 2 f D) f/2

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Question 373

If a convex lens of large aperture fails to converge the light rays incident on it to a single point, it is said to suffer from?

A) chromatic aberration B) spherical aberration C) both spherical and chromatic D) distortion

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Question 374

The least distance of distinct vision for a normal eye is?

A) 15 cm B) 25 cm C) 30 cm D) 40 cm

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Question 375

Image of an object 5 mm high is only 1 cm high. Magnification produced by lens is?

A) 0.5 B) 0.2 C) 1 D) 2

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Question 376

Magnifying power of simple microscope?

A) increase with increase in focal length B) increase with decrease in focal length C) no effect with decrease or increase with focal length D) list distance of distinct vision

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Question 377

A convex lens gives a virtual image only when the objects lies?

A) between principal focus and center of curvature B) beyond 2 f C) at the principal focus D) between principal focus and optical center

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Question 378

If an object is placed away from 2f of a converging lens then the image will be?

A) real and erect B) virtual and erect C) real and inverted D) virtual

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Question 379

The minimum distance between an object and its real image in a convex lens is?

A) 2 f B) 2.5 f C) 3f D) 4f

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Question 380

The power of a concave lens is?

A) real B) virtual C) positive D) negative

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