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Surface Tension is what makes tiny insects “walk” over the water. Fine needles and pins, tin foil sheets, and other miniature objects float on water because of surface tension. Liquid’s surface has a physical property that makes it seem like an elastic film. One by one, water molecules pull each other at the same direction in equal net force of zero. The phenomenon makes the molecules at the water’s surface be drawn inwards by the water molecules inside the liquid. The asymmetrical forces of intermolecular forces among the water’s surface cause it to stretch, attempting to minimize the surface area, thereby creating a thin and elastic membrane. Surface tension is what make water droplets have its almost-spherical shape, too. The stretching of the liquid is evident on a falling drop of water.

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[Origin: 1875–80]

Radiation as described in physics is energy in the form of waves or moving subatomic particles emitted by an atom or another body as it changes from a higher state of energy to a lower energy state or simply as a process of transmitting energy through space. It is classified as ionizing or non-ionizing radiation depending on its effect on atomic matter. There are three types of ionizing radiation: alpha, beta and gamma.

Mechanical radiation consists of waves that are transmitted only through matter, an example of this are sound waves. Electromagnetic radiation is independent matter for its propagation however are influenced by the presence of matter.

A rainbow is an arch of light displaying the spectrum of colors in their order brought about drops of water falling through the air. It is a group of nearly circular arcs of color all having a common center, explaining the “bow” part of it’s name. Rainbows are optical illusions and a meteorological phenomena that take a form of a multicolored arc. It can spring by other forms of water other than rain, including mist, spray, fog and ice. Rainbows are usally seen in the sky opposite to the sun at the spray of waterfalls or close of a shower. Traditionally, the colors of the rainbow are described as made up of seven colors – red, orange, yellow, green, blue, indigo and violet.

Galileo Galilei is an Italian physicist and astronomer who had several contributions to science,physics and astronomy. He discovered the laws of falling bodies and the motions of projectiles in physics, the use of the telescope in observation, the discovery of sunspots, the mountains and valleys of the Moon, the four largest satellites of Jupiter, the phases of Venus in astronomy and collaborated with Johannes Kepler to initiate the scientific revolution. He is considered to be the ‘Father of Modern Observational Astronomy’, the ‘Father of Modern Physics’ and the ‘Father of Modern Science’.

Galileo was a firm believer of heliocentrism, theory suggesting that the sun is the center of the solar system, which was considered against the Catholic Church’s belief in the scriptures because of this Galileo was forced to recant his heliocentrism and was placed in house arrest on orders of the Inquisition.

Vacuum is any space empty of any form of matter, wherein the pressure is a lot less than the atmospheric pressure. This is an ideal concept, and it has yet to be perfectly achieved in a laboratory. However, quantum theory predicts that a perfect vacuum, or space that is totally empty, is non-existent, even in outer space.

A vacuum is created by taking gas out of a container, usually called a vacuum chamber. As gas molecules escape from the chamber, the pressure inside significantly lowers. The chamber must be strong enough to withstand the atmospheric pressure, or it will be crushed.

Practical applications of vacuums include vacuum cleaners, light bulbs and thermos bottles.

Magnetism is a physical phenomenon by which materials attract or repel each other at a distance. Magnetic forces are produced by the movement of electrons in these materials. Materials known to have magnetic properties are called magnets. A magnet has two poles: the north and the south. Like poles repel each other and opposite poles attract. Metallic objects like iron are known to have strong magnetic properties.

Magnetism and electricity have been found to be interrelated. An electric current creates a magnetic field, while a magnetic field is also capable of creating an electric current. The study and science of both fields is called Electromagnetism.

Visible light is a type of electromagnetic (EM) radiation that is visible to the human eye. Other types of EM radiation include microwaves, infrared radiation, ultraviolet radiation and X-rays. “Speed of light” refers to the rate at which all electromagnetic radiation travel in free space. When light passes through a translucent or transparent material, such as glass and ambient air, its speed significantly decreases.

The speed of light is usually denoted by the letter c, and is a physical constant essential to various concepts, including Einstein’s Theory of Relativity. Although c has been defined to be exactly 299,792,458 meters per second (about 186,000 miles per second), it is most commonly used in its rough estimate, 3×10⁸ m/s.