Heat is a fundamental concept in physics. It represents energy that is transferred between systems or objects due to a temperature difference. When two objects at different temperatures come into contact, heat naturally flows from the hotter object to the cooler one until they reach thermal equilibrium.
Heat can be transferred through three main mechanisms. Conduction occurs when heat moves through direct contact between materials, like heat traveling through a metal rod. Convection involves the movement of fluids, where heated fluid rises and cooler fluid sinks, creating circulation patterns. Radiation transfers heat through electromagnetic waves, like the sun warming the Earth across empty space.
Latent heat is a special type of energy that is absorbed or released during phase transitions, such as melting, freezing, boiling, or condensation. Unlike sensible heat, which causes temperature changes, latent heat causes changes in the state of matter while keeping the temperature constant. For example, when ice melts at zero degrees Celsius, it absorbs latent heat to break the bonds between molecules without increasing temperature.
The key difference between sensible heat and latent heat becomes clear when we look at a heating curve. Sensible heat causes temperature changes, following the equation Q equals m c delta T, where we can measure the temperature change with a thermometer. Latent heat, however, causes phase changes at constant temperature, following Q equals m L, where L is the latent heat of fusion or vaporization. During melting and boiling, temperature remains constant even though heat is being added.
Heat and latent heat have numerous real-world applications. Refrigeration systems use latent heat during evaporation and condensation to cool spaces. Steam engines convert latent heat of vaporization into mechanical work. Weather patterns involve latent heat in cloud formation and precipitation. Even cooking processes rely on both sensible and latent heat. In summary, heat is energy transfer due to temperature differences, while latent heat is the energy involved in phase changes at constant temperature.