physics question help plzz?

Question

The space blankets, used by the cosmonaut, are coated by silver from outside because the silver is a ........
(a)good insulator of heat
(b)poor conductor of heat
(c) best radiator of heat
(d)poor radiator of heat
please answer this question.
also i want to know whats the difference between insulator ,conductor and radiator

Answer 1

the foil goes "inside" to reflect heat back to the person in the blanket.

insulator - inhibits the flow of thermal energy
conductor - allows thermal energy to travel through it
radiator - emits thermal energy in the form of infrared light

Answer 2

Of the metals, silver is the best conductor of heat and electricity. Thermal insulators are materials that are poor conductors of heat. They are also called good insulators.

Conductor: A material or an object that conducts heat, electricity, light, or sound. Electrical conductors contain electric charges (usually electrons) that are relatively free to move through the material; a voltage applied across the conductor therefore creates an electric current. Insulators (electrical nonconductors) contain no charges that move when subject to a voltage.

Insulators: A material or an object that does not easily allow heat, electricity, light, or sound to pass through it. Air, cloth and rubber are good electrical insulators; feathers and wool make good thermal insulators.

Radiators: in Physics, A body that emits radiation. Radiators are commonly designed to transfer heat energy from one place to another, as in an automobile, in which the radiator cools the engine by transferring heat energy from the engine to the air, or in buildings, where radiators transfer heat energy from a furnace to the air and objects in the surrounding room.

Answer 3

Insulators and conductors are opposites of each other. When heat is transferred THROUGH a material, the thermal conductivity of the material determines the amount of heat transferred for a given temperature gradient. Radiation has to do with the transfer of heat in a transparent gas or vacuum by virtue of temperature difference between the SURFACE of the radiator and its surroundings. The equation is much different (a 4-th power abolute temperature relation), and the apparent reflectivity of material. Apparently, silver is used because it relectivity is low.

Answer 4

best radiator of heat
the substances in which current can not flow are called insulators whereas the substance in which current can flow easily as there are large number of free electrons in it. radiators are substances which radiate most of the heat incident on it.