IGCSE CIE Thermal Physics Already Graded A+

IGCSE CIE Thermal Physics Already Graded A+ 1. Solid - Solids have a fixed shape and volume. - Molecules are strongly attracted to each other. - They have a fixed pattern in a lattice structure. - Molecules vibrate around fixed positions. 2. Liquid - Liquids have a fixed volume but take the shape of their container. - Forces of attraction between molecules are weaker than in solids. - There is no fixed pattern as molecules can slide past each other. - Molecules move by sliding past one another. 3. Gas - Gases have neither a fixed shape nor volume. - There are very weak intermolecular forces. - Molecules spread to fill the container they are in. - Molecules move freely and collide with each other and the container walls. 4. Heating Material - When materials are heated, molecules gain kinetic energy, causing them to move faster. - This increased internal energy leads to expansion of the material. 5. Brownian Motion - Brownian motion refers to the random movement of tiny particles visible under a microscope. - It occurs due to collisions between particles like smoke and air molecules, causing random directional changes. 6. Evaporation - Evaporation is a continual process occurring at the surface of liquids, where molecules with the highest kinetic energy escape into the air. - As high-energy molecules leave, the average kinetic energy and thus the temperature of the liquid decreases. 7. Factors Affecting Evaporation - Increasing temperature provides more energy to molecules, increasing the rate of evaporation. - Increasing the surface area exposes more liquid molecules to the air, enhancing evaporation. - Reducing humidity lowers the number of water vapor molecules in the air above the liquid, facilitating faster evaporation. - Blowing air across the liquid's surface increases the rate of evaporation by removing water vapor