Ray Optics and Optical Instruments — Physics STD 12 Science — Question

Write and explain the law of conservation of electric charge.

When the last image of the telescope is formed at infinity, then what is the length of its tube? If the image is formed at the minimum distance of clear vision then will the length be less or more than before?

In an electrolyte, the positive ions move from left to right and the negative ions from right to left. Is there a net current? If yes, in what direction?

Define the international definition of ampere.

What is the advantage of using a polygonal mirror with larger number of faces in Michelson method of measuring the speed of light?

When does a charge be source of origin of electromagnetic waves? How are the magnetic field and electric field mutually and with the transmission of wave related? Which physical quantity is same for waves of all parts of electromagnetic classification?

The separation between a node and the next antinode in a vibrating air column is 25cm. If the speed of sound in air is 340m/s, find the frequency of vibration of the air column.

Write down the phenomena seen or observed during the generation of static electricity.

Derive the equation of P.E. (Potential Energy) of an electric dipole in uniform electric field.

Spring fitted doors close by themselves when released. You want to keep the door open for a long time, say for an hour. If you put a half kg stone in front of the open door, it does not help. The stone slides with the door and the door gets closed. However, if you sandwitch a 20g piece of wood in the small gap between the door and the floor, the door stays open. Explain why a much lighter piece of wood is able to keep the door open while the heavy stone fails.