Energy Transfer by Heating P2

Thermal Conductivity

• The thermal conductivity indicates how quickly energy is transmitted through a material by thermal conduction.

• Lower thermal conductivity equates to a lower rate of heat loss, which can be achieved using thermal insulators.

• The rate of energy transfer depends on the material’s thermal conductivity, temperature difference, and thickness.

Specific Heat Capacity

• Specific heat capacity is the energy needed to raise the temperature of 1 kg of a substance by 1 °C.

• The change in thermal energy can be calculated using the formula: E=mc\theta

  • E is the change in thermal energy (J).

  • m is the mass (kg).

  • c is the specific heat capacity (J/kg°C)

  • \theta is the temperature change (°C).

Infrared Radiation

• All objects emit and absorb infrared radiation; hotter objects emit more.

• Good absorbers of infrared radiation are also good emitters.

• At a constant temperature, infrared radiation emitted equals infrared radiation absorbed.

• An object's temperature increases if it absorbs infrared radiation at a higher rate than it emits it.

Earth's Temperature and Greenhouse Gases

• The Earth's temperature depends on reflection, absorption, and emission of light and infrared radiation.

• Greenhouse gases trap infrared radiation, increasing Earth’s temperature.

• Human activities increase greenhouse gases, causing climate change.

Black Body

• A black body absorbs 100% of radiation and is a perfect emitter.

Key Terms

• Absorb: To take in energy or radiation.

• Black Body: A theoretical object that absorbs all radiation.

• Electromagnetic Spectrum: The range of all types of electromagnetic radiation.

• Emit: To give out energy or radiation.

• Greenhouse Gas: A gas that absorbs and re-emits infrared radiation.

• Infrared Radiation: A type of electromagnetic radiation.

• Specific Heat Capacity: The energy required to raise the temperature of 1 kg of a substance by 1 °C.

• Thermal Conductivity: A measure of a material's ability to conduct heat.

• Thermal Insulator: A material with low thermal conductivity.