14.2 – Light Infrared wave: electromagnetic wave with a wavelength shorter than a microwave but longer than light. Ex: Remote controls (TV, DVD player, etc.) use infrared waves. We feel heat from infrared waves (Ex: the sun, a heater, fire.) Intensity: amount of energy that passes through a square meter of space in one second. Opaque: material that light does not pass through. Ex. Wood, metal, cardboard Radio wave: low frequency, low energy electromagnetic wave that has a wavelength longer than about 30cm. Ex: Radios, TVs, Cell phones, satellites, WiFi. Range: set of values from least to greatest. Translucent: material that allows most of the light that strikes it to pass through, but through which objects appear blurry. Ex: Sheer fabric, thin paper, sunglasses. Transparent: material that allows almost all of the light striking it to pass through, and through which objects can be seen clearly. Ex: Clear glass, windows, water, clear plastic. Ultraviolet wave: electromagnetic wave with a slightly shorter wavelength and higher frequency than light. Ex: These waves from the sun cause sunburn; fluorescent light; used to harden substances in dentistry and nail salons.