# Ray Optics-Lens Maker's Formula and Lens Formula (NEET Physics): Questions 8 - 11 of 19

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## Question number: 8

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

### 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 (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 (Ꭺ)

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

### Reason (Ꭱ)

### 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

### 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 |