Test: Thermal Properties & Temperature - 1 - Year 11 MCQ

Internal energy signifies the total energy contained within a system, originating from the motion and positions of its constituent particles. It characterizes the sum of the energies resulting from particle motion and positions relative to each other, rather than being specifically about the energy needed to change the state of a substance.

The material's temperature correlates directly with the average kinetic energy of its molecules. When a system is heated, it raises the kinetic energy of its particles, leading to a direct relationship between temperature and average kinetic energy.

Specific heat capacity, denoted as "c," of a substance is described as the energy needed to raise the temperature of 1 kg of the substance by 1 degree Celsius. It is a measure of how much energy is required to change the temperature of a given mass of a substance.

The formula for calculating specific heat capacity involves the change in thermal energy, mass, specific heat capacity, and change in temperature. It quantifies the amount of energy required to raise the temperature of a given mass by a given amount.

When substances are heated, it's primarily the volume occupied by the molecules that expands, while the molecules themselves maintain their original size. The expansion occurs in the space between molecules, leading to thermal expansion in solids, liquids, and gases.

Thermometers utilize the expansion of liquids to gauge temperature, demonstrating a practical application of the phenomenon of thermal expansion. This principle is employed in various temperature measuring devices for accurate readings.

A substance with a high specific heat capacity heats up and cools down slowly, requiring more energy to change its temperature. This characteristic allows such substances to resist rapid temperature changes compared to those with lower specific heat capacities.

Temperature-activated switches operate by utilizing the bending of a bimetallic strip, composed of two metals expanding at different rates, at specific temperatures. When heated, the bimetallic strip bends upwards, closing the circuit and enabling the switch to activate based on the principle of thermal expansion.

The primary cause of expansion in materials when they are heated is the acceleration of molecular movement or vibration. This increased movement leads to molecules colliding more frequently, exerting force on each other, and pushing each other farther apart, resulting in thermal expansion.

Materials with low specific heat capacities require less energy to alter their temperature compared to those with high specific heat capacities. This characteristic makes them heat up and cool down rapidly, showcasing a distinctive difference in behavior based on specific heat capacity.