Understanding Heat, Temperature, and Energy Transmission

1. Heat: Heat is the energy created by the movement of atoms and molecules (groups of atoms). For example, thermal energy can be converted into heat. To increase a body's heat, its molecules must increase their speed. 2. Temperature: Temperature is a measure of the heat or thermal energy of the particles in a substance. It expresses the level of a body's heat. Thermal agitation is seen in the vibration of atoms or molecules of a body due to the amount of internal energy or heat it possesses. 3. Effects of Heat:

• Temperature Changes: When a body absorbs heat, its temperature increases.
• Resizing: When a body is heated, its heat energy increases, causing the body to expand and increase in volume.
• State Change: Heat can cause a body to change its state from solid to liquid, liquid to gas, or gas to liquid.

4. Propagation of Heat:

• Conduction: Heat is transmitted by contact. This type of transmission is characteristic of solid bodies, and the body must be a good heat conductor.
• Convection: This is a form of energy propagation that occurs in liquids and gases.
• Radiation: Energy is spread through space without requiring the presence of matter.

5. Transmission of Energy: Energy can be transmitted to other bodies. Some processes allow transmission between bodies even when they are separated. These processes include the emission and absorption of sound or light. Light is radiant energy, composed of particles called photons that propagate through space. In a vacuum, light travels at 300,000 km/s. There are several ways to produce light, all characterized by the existence of matter at high temperatures. Incandescent bodies emit photons that propagate as waves in all directions and are absorbed by other bodies. The trajectories of photons can be indicated by imaginary straight lines called rays. Sound is a mechanical vibration that propagates through matter. Its speed in air is 340 m/s, while in steel, the speed is 5,100 m/s. 6. Reflection and Refraction of Light: When we look in a mirror, we see our image because light bounces off it and comes to our eyes. The same happens with sound. Reflection is a phenomenon characteristic of waves. The reflection of light occurs in a similar manner. 7. Matter and Light Colors: According to the behavior of different materials with light, they can be classified into:

• Transparent Materials: These allow photons to pass through without absorption. Details of objects can be seen clearly.
• Translucent Materials: These allow photons to pass but deviate them in all directions. Details of objects behind them are not clearly known.
• Opaque Materials: These absorb some photons and return the rest to the environment. Objects behind them cannot be seen.