Choose the correct alternative and rewrite statement.
Chapter No. 7: Lenses
A ________ lens always produces virtual and diminished image.
A. Biconvex
B. Biconcave
C. Planoconvex
D. Bifocal
While finding the focal length of convex lens, the image obtained is _______
A. real and erect
B. real and inverted
C. virtual and erect
D. virtual and inverted
According to Cartesian sign conventions for lenses
A. all distance in direction of incident ray are taken positive.
B. all distances in direction of incident ray are taken negative.
C. height above the principal axis is negative for concave lens.
D. height above the principal axis is negative for convex lens.
A student obtains a clear image of a candle on a screen with the help of a convex lens. He now wants to focus on a distant tree and obtain a clear image. In which direction would he move the lens in order to get a clear image?
A. Behind the screen
B. Away from the screen
C. Towards the screen
D. At a very long distance from the screen.
To obtain an image of the same size as that of an object using a convex lens, the object should be placed __________
A. at 2F2
B. Between F2 and 2F1
C. at 2F1
D. at infinity
If radius of curvature of a biconvex lens is increased, without changing the thickness of the lens, then focal length of the lens will _________
A. be decreased
B. remain unchanged
C. be increased
D. be first decreased and then increased.
For a particular glass lens F = - 4 m. Only this much data was provided to a student. He was told to calculate the power of lens and to find out type of lens given to him. His answer must be __________
A. Power: +2 dioptre; Convex lens
B. Power: +1 dioptre; Concave lens
C. Power: - 0.25 dioptre; Concave lens
D. Power: - 2 dioptre; Convex lens
A refracting telescope is made of _________
A. two convex lenses
B. one concave mirror, one plane mirror and one convex lens.
C. one convex lens and concave mirror.
D. one concave mirror, one convex mirror and one convex lens.
Answers:
Chapter No. 7: Lenses
A ________ lens always produces virtual and diminished image.
A. Biconvex
B. Biconcave
C. Planoconvex
D. Bifocal
While finding the focal length of convex lens, the image obtained is _______
A. real and erect
B. real and inverted
C. virtual and erect
D. virtual and inverted
According to Cartesian sign conventions for lenses
A. all distance in direction of incident ray are taken positive.
B. all distances in direction of incident ray are taken negative.
C. height above the principal axis is negative for concave lens.
D. height above the principal axis is negative for convex lens.
A student obtains a clear image of a candle on a screen with the help of a convex lens. He now wants to focus on a distant tree and obtain a clear image. In which direction would he move the lens in order to get a clear image?
A. Behind the screen
B. Away from the screen
C. Towards the screen
D. At a very long distance from the screen.
To obtain an image of the same size as that of an object using a convex lens, the object should be placed __________
A. at 2F2
B. Between F2 and 2F1
C. at 2F1
D. at infinity
If radius of curvature of a biconvex lens is increased, without changing the thickness of the lens, then focal length of the lens will _________
A. be decreased
B. remain unchanged
C. be increased
D. be first decreased and then increased.
For a particular glass lens F = - 4 m. Only this much data was provided to a student. He was told to calculate the power of lens and to find out type of lens given to him. His answer must be __________
A. Power: +2 dioptre; Convex lens
B. Power: +1 dioptre; Concave lens
C. Power: - 0.25 dioptre; Concave lens
D. Power: - 2 dioptre; Convex lens
A refracting telescope is made of _________
A. two convex lenses
B. one concave mirror, one plane mirror and one convex lens.
C. one convex lens and concave mirror.
D. one concave mirror, one convex mirror and one convex lens.
