An insulator is a material or method that restricts the transfer of either heat or electricity. Insulators are used to protect us from the dangerous effects of electricity flowing through conductors. Insulators are materials that have just the opposite effect on the flow of electrons. They do not let electrons flow very easily from one atom to another. Insulators are materials whose atoms have tightly bound electrons. These electrons are not free to roam around and be shared by neighboring atoms. Some common insulator materials are glass, plastic, rubber, air, and wood. Most solid materials are classified as insulators because they offer very large resistance to the flow of electric current. A material used to resist the flow of heat is known as “Thermal insulation”. Thermal insulators work by reducing the rate heat can travel through a space. Basically, they use specific materials which will keep heat-carrying matter from moving. On the other hand, in case of electricity, Electrical insulators detain the electric current to a chosen path. They generally work by using a material with many outer electrons, a condition that will cause low electrical conductivity.
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat is the transfer of thermal energy between objects of differing temperature. The means to stem heat flow may be especially engineered methods or processes, as well as suitable static objects and materials. Heat flow is an inevitable consequence of contact of objects of differing temperature. Thermal insulation provides a means to maintain a gradient of temperature, by providing a region of insulation in which heat flow is reduced or thermal radiation is reflected rather than absorbed. A thermal insulator assists in keeping an object at a constant temperature, no matter hot or cold. It typically works by two processes, either conduction or convection, which are two methods of heat transfer.
Convection, on the other hand, is internal heat carried with moving matter; this happens when wind carries heat away from one’s body.
Thermal conductivity ("k" value) is the property of a material's ability to conduct heat. A thermal insulator functions by reducing the rate heat that can move through an area. The rate of conductive heat transfer is proportional to the thermal conductivity. For example, copper transfers heat quickly because of its high-thermal conductivity. A good insulator, therefore, has low-thermal conductivity. In fact, air has a low conductivity, but it tends to move around a lot. A blanket acts as a thermal insulator since it pushes air to transfer heat through conduction instead of convection. Other factors such as insulation thickness, density and specific heat capacity (the measurable physical quantity that characterizes the amount of heat required to change a body's temperature by a given amount) also affects thermal insulation. It is important to note that the factors influencing performance may vary over time as material ages or environmental conditions change.
An insulator, also called a ‘dielectric’, is a material that resists the flow of electric charge. In insulating materials valence electrons (outermost electrons in the atoms) are tightly bonded to their atoms. These materials are used in electrical equipment as insulators or insulation. Their function is to support or separate electrical conductors without allowing current through themselves. Some materials such as glass, paper or Teflon are very good electrical insulators and are "good enough" to insulate electrical wiring and cables. Most plastics can serve as practical and safe insulators for low to moderate voltages (hundreds, or even thousands, of volts). Electrical insulation is the absence of electrical conduction. Electronic band theory (a branch of physics) says that a charge will flow if states are available into which electrons can be excited. This allows electrons to gain energy and thereby move through a conductor such as a metal. If no such states are available, the material is an insulator.
Many factors affect electrical conductivity, including temperature, but elements tend to have either high or low conductivity. This is due to the fact that different elements have a different number of outer electrons, which changes how easy it is to free those electrons. Metals, for instance, are likely to have high conductivity because their outer electrons are easy to free.