Test: Transfer of Thermal Energy - 1 - Year 11 MCQ

In solids, the primary method of thermal energy transfer is conduction. This process involves the transfer of thermal energy when two solids of different temperatures come into contact. Metals, in particular, are exceptional conductors due to their high number of free electrons, which allow for efficient transfer of thermal energy.

Metals are exceptional thermal conductors due to their high number of free electrons. These free electrons enable metals to effectively transfer thermal energy through the material, making them efficient at conducting heat compared to non-metallic solids.

In solids, conduction occurs through atomic vibrations. When a solid is heated, its atoms vibrate, transferring energy through the material. This vibration leads to collisions between atoms, facilitating the transfer of thermal energy from one atom to another, until the substance reaches thermal equilibrium.

Both liquids and gases exhibit poor heat conductivity. While particles in liquids are close together, they tend to slide past each other, hindering efficient heat transfer. Gases, on the other hand, have widely spaced particles, limiting their capacity to effectively transmit heat.

Materials that do not transfer heat well are known as insulators. Insulators, such as woolen blankets or layers of cardboard, are poor thermal conductors and are used to prevent the loss of heat.

Tiles feel cold because they have high thermal conductivity, allowing them to efficiently conduct heat away from objects in contact with them. On the other hand, textiles like rugs act as insulators with low thermal conductivity, which means they do not conduct heat away as effectively, leading to a warmer sensation when touched.

Changes in temperature leading to changes in density, known as thermal expansion, are responsible for initiating convection currents. When a liquid or gas is heated, it expands and becomes less dense, leading to the rise of warmer substances and the descent of cooler substances, creating a convection current.

Convection exclusively takes place within fluids, specifically in liquids. Solids do not facilitate convection as their particles are not free to move and flow like those in liquids and gases.

Introducing crystals of potassium permanganate to warm water showcases convection in liquids. As heat is applied to one side of the beaker, causing the water to warm up, the potassium permanganate dissolves and moves with the heated water, demonstrating the movement of the convection current.

Heat primarily propagates through liquids and gases via convection. Convection involves the transfer of heat through the movement of the fluid itself, as warmer, less dense fluid rises and cooler, denser fluid sinks, creating a cycle of heat transfer.