# Ray Optics (NEET Physics): Questions 38 - 41 of 105

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## Question number: 38

» 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: 39

» 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: 40

» Ray Optics » Deviation and Dispersion of Light by a Prism

Assertion-Reason▾

### Assertion (Ꭺ)

Dispersion of light occurs because velocity of light in a material depends upon its color.

### Reason (Ꭱ)

The dispersive power depends only upon the material of the prism, not upon the refracting angle of the prism.

### Choices

Choice (4) Response

a.

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

b.

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

c.

Ꭺ is false but Ꭱ is true

d.

Both Ꭺ and Ꭱ are false

## Question number: 41

» Ray Optics » Reflection and Refraction of Light » Smooth Surface

MCQ▾

### Question

In an experiment to determine the focal length (f) of a concave mirror by the u - v method, a student places the object pin A on the principal axis at a distance x from the pole P. The student looks at the pin and its inverted image from a distance keeping his/her eye in line with PA. When the student shifts his/her eye towards left, the image appears to the right of the object pin. Then,

### Choices

Choice (4) Response

a.

x < f

b.

x = 2 f

c.

f < x < 2f

d.

x > If

f Page