Electric Field and Potential — Physics STD 11 Science — Question

A man stands before a large wall at a distance of 50.0m and claps his hands at regular intervals. Initially, the interval is large. He gradually reduces the interval and fixes it at a value when the echo of a clap merges with the next clap. If he has to clap 10 times during every 3 seconds, find the velocity of sound in air.

Light of wavelength 560nm goes through a pinhole of diameter 0.20mm and falls on a wall at a distance of 2.00m. What will be the radius of the central bright spot formed on the wall?

State Wien's law. Write the S.I. unit of Wien's constant.

A charge Q is placed at the centre of an imaginary hemispherical surface. Using symmetry arguments and the Gauss's law, find the flux of the electric field due to this charge through the surface of the hemisphere (figure).

Explain why
A drop of liquid under no external forces is always spherical in shape.

Two syringes of different cross-sections (without needles) filled with water are connected with a tightly fitted rubber tube filled with water. Diameters of the smaller piston and larger piston are 1.0cm and 3.0cm respectively.

1. Find the force exerted on the larger piston when a force of 10N is applied to the smaller piston.
2. If the smaller piston is pushed in through 6.0cm, how much does the larger piston move out?

Can virtual image be formed on the retina in a seeing process?

What is the specific heat capacity of:

1. Melting ice
2. Boiling water?

A point source is placed at a depth h below the surface of water (refractive index = μ).

1. Show that light escapes through a circular area on the water surface with its centre directly above the point source.
2. Find the angle subtended by a radius of the area on the source.