Light - IR - 14-16
This collection explores Infra-Red light, suitable for ages 14-16
About Infra-Red Light:
Infrared (IR) is invisible radiant energy, electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 700 nanometers (frequency 430 THz) to 1 mm (300 GHz). Most of the thermal radiation emitted by objects near room temperature is infrared.
Infrared radiation was discovered in 1800 by astronomer Sir William Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect upon a thermometer. Slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has a critical effect on Earth's climate.
Resources in this collection:
- Infra-Red: More Than Your Eyes Can See: From NASA, this short video looks at how infra-red cameras see the world and are used to explore space. It describes the electromagnetic spectrum and how infra-red is a measure of heat radiation.
- Invisible Rays: A Catalyst article about the astronomer William Herschel who discovered Uranus in 1781. He became the first person since ancient times to identify a new planet. However, he is also known as the ‘accidental’ discoverer of infrared radiation. The article asks is this a fair description and can such discoveries really happen by accident?
- Invisible Wavelengths: This Teaching Astronomy and Space video clip, from the Institute of Physics (IOP), Teachers TV and the Science and Technology Facilities Council (STFC), shows a simple demonstration to illustrate wavelengths of radiation that are invisible to the human eye, but which can be detected using a camera phone or digital camera. The camera of a mobile phone or digital camera can detect wavelengths near infrared. These are the wavelengths used by remote controls for televisions and other consumer electronics. Whilst the human eye cannot detect the wavelength, pressing the control buttons will show as a flashing emitter on the remote control.
- Pulse Oximeters: This resource from the Institute of Physics (IOP), describes how light can be used in pulse oximetry to measure pulse rate and oxygen levels in the body.
- Radiation and communication: Remote controls, mobile phones, televisions and radios are such commonplace devices that it is easy to take for granted how they work. What they have in common is that electromagnetic radiation is used to send messages from a transmitter to a receiver with no physical connection between them. This ‘action-at-a-distance’ has become a familiar part of everyday life. The booklet focuses on the scientific principles underlying the use of electromagnetic radiation in communication devices, from visible light through to radio waves.
