# Ray Optics-Lens Maker's Formula and Lens Formula (NEET (NTA)-National Eligibility cum Entrance Test (Medical) Physics): Questions 12 - 17 of 19

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## Question number: 12

» Ray Optics » Lens Maker's Formula and Lens Formula

MCQ▾

### Question

A convex lens of focal length 20 cm is placed in contact with a diverging lens of unknown focal length. The lens combination acts as a converging lens and has a focal length of 30 cm. What is the focal length of the diverging lens

### Choices

Choice (4) Response

a.

- 30 cm

b.

- 60 cm

c.

- 10 cm

d.

- 90 cm

## Question number: 13

» Ray Optics » Lens Maker's Formula and Lens Formula

MCQ▾

### Question

In case of thin lens of focal length an object is placed at a distance from first focus and its image is formed at a distance from the second focus, find

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 14

» Ray Optics » Lens Maker's Formula and Lens Formula

MCQ▾

### Question

For a Plano-convex lens of radius of curvature 10 cm, the focal length is 30 cm, if the refractive index of the material of the lens is,

### Choices

Choice (4) Response

a.

1.5

b.

1.33

c.

1.66

d.

2.0

## Question number: 15

» Ray Optics » Lens Maker's Formula and Lens Formula

MCQ▾

### Question

Two thin lenses of focal length 60 & -20 cm in contact have a resultant focal length of,

### Choices

Choice (4) Response

a.

-15 cm

b.

+30 cm

c.

+15 cm

d.

-30 cm

## Question number: 16

» Ray Optics » Lens Maker's Formula and Lens Formula

MCQ▾

### Question

An image is formed on the screen by a convex lens. When upper half part of lens is covered with black paper, then:

### Choices

Choice (4) Response

a.

Half image is formed

b.

Intensity of image will be enhanced

c.

Full image is formed

d.

None of the above

## Question number: 17

» Ray Optics » Lens Maker's Formula and Lens Formula

MCQ▾

### Question

A pin is placed 10 cm in front of a convex lens of focal length 20 cm, made of material having refractive index 1.5. The surface of the lens farther away from the pin is silvered and has a radius of curvature 22 cm. determine the position of the final image.

### Choices

Choice (4) Response

a.

31 cm in front

b.

11 cm in front

c.

15 cm in front

d.

21 cm in front

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