The Science of Heat: Conduction, Temperature, and Energy Transfer

Conductors and Insulators

Materials that transmit heat well, such as metals like iron, are known as good conductors.

Materials that transmit heat poorly are known as bad heat conductors or insulators.

The Effects of Heat

Heat produces changes when it passes from one body to another. The primary effects include:

• Increases the temperature of bodies: This is the most noticeable change and the one we are most used to.
• Changes the state of bodies: For example, heat can melt ice and convert it into water.
• Expands bodies: This change is not generally noticeable to the naked eye.

Heat vs. Temperature: What's the Difference?

Many people confuse the concepts of heat and temperature. Although they are related, they are not the same.

Heat is a form of energy that is transmitted. When two bodies at different temperatures make contact, heat passes from the one at a higher temperature to the one at a lower temperature. Heat can be transformed into other forms of energy, such as kinetic energy or light energy.

Temperature tells us how hot or cold a physical body is. The temperature of a body is related to the quantity of heat that can be released or absorbed by that body.

Measuring Temperature

Temperature is measured with a thermometer. Thermometers are based on some of the effects that heat produces on bodies, such as expansion.

Temperature Scales

Temperature can be expressed using different scales:

• The Celsius (or Centigrade) scale
• The Fahrenheit scale
• The Kelvin scale

The Kelvin scale, or absolute scale, is used principally in scientific areas. On this scale, temperature is measured in Kelvins (K).

Mechanisms of Heat Transmission

Heat is transmitted by means of different mechanisms: conduction, convection, and radiation.

Transmission by Conduction

The transmission of heat by conduction occurs in solids, but not all solids transmit heat to the same extent.

• Solids that transmit heat well, such as metals, are called conductors.
• Solids that transmit heat poorly, such as wood and many plastics, are called insulators.

Transmission by Radiation

The transmission of heat by radiation occurs when energy is transmitted in the form of waves. This is the quickest way to transmit heat. The amount of heat transmitted by radiation depends on the temperature; the higher the temperature, the more heat will be radiated.

Sun Safety and Radiation

Burns from the sun are caused by heat transmission through radiation. To protect yourself:

• Do not stay in the sun for too long.
• Protect your skin with sun cream.
• Cover especially sensitive areas that are not often exposed to the sun, like your back and feet.