Energy Resources and Transfer: Energy Transfer by Heating

Energy Resources and Transfer: Energy Transfer by Heating

  • Energy can be transferred from one place to another by conduction, convection, and radiation.

  • Conduction refers to the energy transfer between materials that are in direct contact. In solids, the particles vibrate and pass the energy to the neighbouring particles. This process continues throughout the material until the energy is transferred from one end to the other.

  • Metals are good conductors due to the presence of free electrons that can rapidly pass energy from one particle to another. Non-metals and gases are usually poor conductors because they lack free electrons. This makes them good insulators.

  • Convection is a process of energy transfer through fluids, i.e. liquids and gases. Fluids rise when warmed as the particles move faster and spread out, reducing the density. This leads to upward movement or convection current. As the fluid rises, it cools, falls and then reheats, continuing the cycle.

  • Unlike conduction and convection which require a medium, radiation, specifically infrared radiation, can travel through a vacuum, like space. All objects emit and absorb this type of radiation. The hotter an object is, the more infrared radiation it emits.

  • The efficiency of energy transfer can be improved by reducing unwanted energy losses. Using thermal insulation such as fibreglass in houses reduces energy loss through conduction and convection. Reflective surfaces can prevent energy loss through radiation.

  • Specific heat capacity denotes the energy needed to raise the temperature of 1 kg of a substance by 1 degree Celsius. It varies from material to material. This concept helps us to determine how much energy is absorbed or released when the temperature of a particular material changes.

  • The formula for calculating heat change is: Q = mcΔT, where Q = thermal energy (joules, J), m = mass (kilogrammes, kg), c = specific heat capacity (J/kg°C), and ΔT = temperature change (°C).

  • Energy is always conserved in energy transfer: it cannot be created or destroyed but can be changed from one form to another. This is known as the Principle of Conservation of Energy.

  • The rate of cooling of an object is affected by factors such as its surface area and volume, the nature of its surface, and the temperature difference between the object and its surroundings. Larger objects or those with larger surface areas cool more quickly.