# Ray Optics-Lens Maker's Formula and Lens Formula (NEET (NTA)-National Eligibility cum Entrance Test (Medical) Physics): Questions 8 - 11 of 19

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## Question number: 8

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

MCQ▾

### Question

A convex lens of focal length 10.0 cm is placed in contact with a convex lens of 15.0 cm focal length. What is the focal length of the combination?

### Choices

Choice (4) Response

a.

4 cm

b.

12 cm

c.

8 cm

d.

6 cm

## Question number: 9

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

Assertion-Reason▾

### Assertion (Ꭺ)

The focal length of lens changes when red light is replaced by blue light.

### Reason (Ꭱ)

The focal length of lens does not depend on color of light used.

### Choices

Choice (4) Response

a.

Ꭺ is false but Ꭱ is true

b.

Both Ꭺ and Ꭱ are false

c.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

d.

Ꭺ is true but Ꭱ is false

## Question number: 10

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

Assertion-Reason▾

### Assertion (Ꭺ)

A double convex lens has focal length 10 cm. When the lens is immersed in water its focal length becomes 40 cm.

### Choices

Choice (4) Response

a.

Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ

b.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

c.

Ꭺ is false but Ꭱ is true

d.

Both Ꭺ and Ꭱ are false

## Question number: 11

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

MCQ▾

### Question

A convex lens is made out of a substance of 1.2 refractive index. The two surfaces of lens are convex. If this lens is placed in water whose refractive index is 1.33 it will behave as:

### Choices

Choice (4) Response

a.

Plane glass plate

b.

like a prism

c.

Convergent lens

d.

divergent lens

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