Two plane mirrors are inclined at angle 60° to each other. A ray of light makes
an angle of 40' with mirror M and goes
on to strike mirror M. Find the angle of
reflection on the second mirror M​

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

answer a fan shaped mass of sediment deposited at the base of a mountain front do to an abrupt change in stream gradient;