If the focal length of the objective lens is increased then magnifying power of:

1. microscope will increase but that of the telescope
    decrease.

2. microscope and telescope both will increase.

3. microscope and telescope both will decrease.

4. microscope will decrease but that of the telescope
    will increase.

A microscope is focussed on a mark on a piece of paper and then a slab of a glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again?

1. 1 cm upward

2. 4.5 cm downward

3. 1 cm downward

4. 2 cm upward