Ch. 12 Online Test

The total energy of all the particles in a body is referred to as thermal energy. This energy is associated with the random motion of particles within a substance. It represents the sum of the kinetic and potential energies of the particles, which increases with temperature. Thermal energy is responsible for the transfer of heat, as well as the ability of a substance to conduct or store heat.

An insulator is a material that restricts or limits the transfer of heat. It has low thermal conductivity, meaning it does not allow heat to easily pass through it. This property makes insulators useful for preventing heat loss or gain in various applications, such as in building insulation or thermal clothing.

Radiation is a form of energy that travels from the Sun through space. It is the transfer of energy through electromagnetic waves or particles. The Sun emits radiation in the form of visible light, ultraviolet rays, and infrared radiation. This energy travels through the vacuum of space and reaches the Earth, providing heat and light. Radiation is an essential source of energy for life on Earth and plays a crucial role in various natural processes, such as photosynthesis.

A conductor is a material that allows heat to pass through it easily. Conductors have high thermal conductivity, which means that they have a high ability to transfer heat. This is because conductors have loosely bound electrons that are free to move and transfer thermal energy. Examples of conductors include metals like copper and aluminum.

A convection current is a process in which a heated liquid or gas rises and is replaced by cooler liquid or gas. This occurs due to the difference in density between the hot and cold substances. As the heated substance becomes less dense, it rises while the cooler substance, being more dense, sinks. This continuous movement of hot and cold substances creates a convection current.

Conduction is the transfer of energy from one object to another through direct contact. When two objects are in contact, the particles in the hotter object vibrate more and collide with the particles in the cooler object, transferring energy. This process continues until both objects reach thermal equilibrium. Therefore, conduction is the correct answer for the transfer of energy by one object touching another.

When an object cools down, the particles within it lose energy and move at a slower pace. This decrease in speed is reflected in the word "slower," which is the correct answer.

When the liquid in a thermometer contracts, it means that the substance being measured is cooling down. This is because as the temperature decreases, the particles in the substance slow down and become more compact, causing the liquid in the thermometer to contract. Therefore, the correct answer is that the substance is cooling down.

Radiation is the method of heat transfer that does not require matter. It is the transfer of heat through electromagnetic waves, such as infrared radiation, without the need for a medium to carry the heat. Unlike conduction and convection, which require the presence of matter to transfer heat, radiation can occur in a vacuum or through transparent mediums. Insulation, on the other hand, is a material used to slow down the transfer of heat through conduction or convection, but it still requires matter for heat transfer to occur.

Plastic, wood, and marble are all insulators because they have high resistance to the flow of electricity. Unlike metals, which are conductors, these materials do not allow the free movement of electrons. Insulators are commonly used to prevent the flow of electricity, protect against electric shocks, and provide insulation in various applications.