In a thermos flask, the silvered walls reflect and radiate the heat to the outside.

in thermos flask, the bacuum between the two walls prevents heat from the inside to the outside by radiation.

A hemispherical portion of the surface of a solid glass sphere (mu = 1.5) of radius r is silvered to make the inner side reflecting. An object is placed on the axis of the hemisphere at a distance 3r from the centre of the sphere. The light from the object is refracted at the unsilvered part, then reflected from the silvered part and again refracted at the unsilvered part. Locate the final image formed.

What is the function of silvered wall in a thermos flask?

(I) Repetition of sound produced by the reflection of sound waves from a wall is echo. (II) In a closed room, the sound is repeatedly reflected from the walls and it is heard even after the sound source is ceased, it is called reverberation? Which one is correct?

A hollow tube has a length l, inner radius R_(1) and outer radius R_(2) . The material has a thermal conductivity K. Find the heat flowing through the walls of the tube if (a) the flat ends are maintained at temperature T_(1) and T_(2) (T_(2)gtT_(1)) (b) the inside of the tube is maintained at temperature T_(1) and the outside is maintained at T_(2) .

The angle of a prism is A , One of its refracting surface is slivered . Light rays falling at an angle of incidence 2A on the first surface returns back through the same pathe after suffering reflection at the silvered surface. The refractive index mu of the prism is:

Find whether the following sentences are true or false. If false Correct th statement. The walls of the heat is made up of cardiac muscle.

A siren is fitted on as car going towards a vertical wall at a speed of 36 km/h. A person standing on the ground, behind the car, listens to the siren sound coming directly from the source as well as that coming after refelction from the siren to the person and b. coming after reflection. Take the speed of sound to be 340ms^-1