Some examples of luminous objects are a burning candle, a light bulb, the sun and other stars, fluorescent materials and tube lights, among other things. Any object is considered luminous if it emits its own light, either through stored energy or energy supplied to the object, which contrasts with non-luminous objects such as the moon, wood, plastics and metals; these objects merely reflect light instead of providing their own.Know More
Luminous objects are responsible for our vision, as the human eye only perceives light that is being reflected into it. In darkness, where no luminous objects are present, the eye cannot perceive its surroundings.
In order for luminous objects to emit light, there must be a power source. The sun and other stars produce light due to the fusion of hydrogen atoms, the light bulb emits light due to the electrical energy flowing through it and the lit candle uses energy released by burning the wick. Fluorescent materials store energy given by other luminous objects and release light in wavelengths that cannot be seen in visible light. Some living organisms, such as fireflies, have natural luminescence, which allows them to convert the chemical energy stored in their cells into light. All luminous objects also release heat with the light they generate.Learn More
Types of things that are not considered matter include any type of energy, and abstract concepts. Everything in the universe that contains mass is made of matter. However, there are several things, such as heat, light and other forms of energy, that are not considered matter because they lack mass.Full Answer >
Force multipliers, also known as simple machines, are devices that are able to provide greater output force than input force. Levers, pulleys, ramps, screws, axles and wedges are all force multipliers that operate using basic physical principles in order to increase output force and make work easier.Full Answer >
Sand is heavier than water when the volume of both substances is equal. The density of dry sand is between 80 and 100 pounds per cubic foot, whereas water is 62 pounds per cubic foot. The density of water depends on its temperature.Full Answer >
Naphthalene sublimes easily because it has a low triple point. A substance's triple point is the temperature and pressure at which it can exist in all three phases of matter: solid, liquid and gas. Under ordinary atmospheric pressure, naphthalene's triple point is 176 degrees Fahrenheit.Full Answer >