Ray Optics Test

Result

Ray Optics Test - 38

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Weekly Quiz Competition

Question 1
4 / -1

A combination is made of two lenses of focal length f and f’ in contact, the dispersive powers of the materials of the lenses are ω and ω’. The combination is achromatic, when

A

B

C

D

Solution
Question 2
4 / -1

Two thin lenses of focal lengths f₁ and f₂ are made of materials of dispersive powers ω₁ and ω₂ respectively. The lenses are kept in contact. The combination will show no chromatic aberration, if

A

B

C

D

Solution
Question 3
4 / -1

What is longitudinal spherical aberration in case of a lens which focusses central rays at 20.3 cm and marginal rays at 20.1 cm.

A
0.2 cm

B
0.4 cm

C
Zero

D
None of these
Question 4
4 / -1

Two convex lenses L₁ and L₂ are coaxially placed with respect to each other as shown in Fig. which also shows the position F₁ and F₂ of their focal points. An object OP placed in front of the lens L₁ forms an image AB close to F₂ between F₂C₂. The final image as seen by the eye will be formed

A
inverted and will be beyond the object at a distance greater than C₁ C₂

B
inverted and will be formed at infinity

C
erect and will be formed between C₁ and C₂

D
inverted and will be formed between C₁ and C₂
Question 5
4 / -1

The focal lengths of objective and eye lens of an astronomical telescope are respectively 2 meter and 5 cm. Final image is formed at (i) least distance of distinct vision (ii) infinity. Magnifying power in two cases will be

A
– 48, – 40

B
– 40, – 48

C
– 40, + 48

D
– 48, + 40

Solution
Question 6
4 / -1

The focal length of a convex lens is 2.5 cm. Its magnifying power will be 25

A
25

B
52

C
11

D
1.1

Solution
Question 7
4 / -1

The f number of a camera lens is 4.5. Which of the following statements is correct?

A
The focal length of the lens is 4.5 cm

B
It is the reciprocal of the focal length expressed in metres

C
The ratio of focal length of lens to the aperture is 4.5

D
The aperture of the lens is 4.5 cm

Solution
Question 8
4 / -1

How should people wearing spectacles work with a microscope?

A
They should keep on wearing their spectacles

B
They should take off their spectacles

C
They may keep on wearing or take off their spectacles, it makes no difference

D
They cannot use a microscope at al
Question 9
4 / -1

A person cannot see the objects beyond 100 cm. The power of a lens to correct this vision will be

A
+ 2 D

B
– 1 D

C
+ 5 D

D
0.5 D

Solution
Question 10
4 / -1

A person cannot see an object lying beyond 80 cm, whereas a normal person can easily see the object distant 160 cm. The focal length and nature of the lens used to rectify this defect will be

A
-160 cm, concave

B
-160 cm, convex

C
60 cm, concave

D
160 cm, convex

Solution