Physics

Incoming heat being absorbed by the Earth, and outgoing heat escaping the Earth in the form of radiation are both perfectly balanced. If they were not balanced, then Earth would be getting either progressively warmer or progressively cooler with each passing year. This balance between incoming and outgoing heat is known as Earth’s heat budget.

We measure sound intensity (also referred to as sound power or sound pressure) in units called decibels.

Johannes Kepler was a 16th century astronomer who established three laws which govern the motion of planets around the sun. These are known as Kepler’s laws of planetary motion.

Freezing point is the temperature where a liquid converts into solid. Water converts into ice at zero degrees centigrade. So degree zero centigrade is the freezing point of water.

According to the second law of motion for a given force, the acceleration of the object is inversely proportional to the mass of the object. Therefore, more the mass less is the acceleration and vice versa.

We measure sound intensity (also referred to as sound power or sound pressure) in units called decibels. Decibels (dB) are named in honor of Alexander Graham Bell, the inventor of both the telephone and the audiometer.

A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification, since it “straightens” the direction of current.

Fleming’s right-hand rule (for generators) shows the direction of induced current when a conductor attached to a circuit moves in a magnetic field. It can be used to determine the direction of current in a generator’s windings.

The wavelength of sound changes with temperature. This is because the speed of sound changes with the temperature. Since the speed of sound is different at different temperature, this means the wavelength of sound at a given frequency is a variable depending on the speed of sound. For example, the wavelength of a 100 cycle tone in air at 68ºF would be 11.27 feet while the same tone in fresh water at 68ºF would have a wavelength of 48.05 feet.

When detergent is added to water, it decreases the surface tension of the water. Compounds that lower water’s surface tension are called surfactants, which work by separating the water molecules from one another.