# General Science: Physics – 1

Physics is the natural science that studies matter, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.

#### Ans: Neutral

⇒ Atoms are electrically neutral because they have equal numbers of protons (positively charged) and electrons (negatively charged). If an atom gains or loses one or more electrons, it becomes an ion.

#### Ans: Nitrogen

⇒ Nitrogen is an inert gas. Inert gases reduce the rate of evaporation rate of tungsten metal used in Filament of bulbs. Thus it increases the efficiency of bulbs. That’s why the bulbs are filled with nitrogen

#### Ans: Resistance

⇒ The ohm (symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist and mathematician Georg Simon Ohm.

#### Ans: Isaac Newton

⇒ The ‘Corpuscular theory of light was proposed by Newton in 1704. In this theory, he successfully explained the nature of light. The corpuscular theory is the simplest theory of light in which light is assumed as the tiny particles called ‘corpuscles’, that always travel in a straight line.

#### Ans: Kinetic friction

Kinetic Friction. If two systems are in contact and moving relative to one another, then the friction between them is called kinetic friction. Imagine, for example, trying to slide a heavy crate across a concrete floor—you may push harder and harder on the crate and not move it at all.

#### Ans: Beta-rays

⇒ Beta (β) radioactivity was first observed in the form of a mysterious ray that was deflected by electromagnetic fields in the opposite direction from alpha radiation. The radiation was therefore known to consist of negatively charged particles. After J.J. Thomson discovered (a little before in 1897), the fundamental carrier of negative electric charge, the electron, beta radiation was quickly found to be made up of the same particles.

#### Ans: Two unit positive charges

⇒ Alpha particle, positively charged particle, identical to the nucleus of the helium-4 atom, spontaneously emitted by some radioactive substances, consisting of two protons and two neutrons bound together, thus having a mass of four units and a positive charge of two unit.

#### Ans: Silicon and Germanium

⇒ Silicon. In solid state electronics, either pure silicon or germanium may be used as the intrinsic semiconductor which forms the starting point for fabrication. Each has four valence electrons, but germanium will at a given temperature have more free electrons and a higher conductivity.

#### Ans: Centripetal force

⇒ A centripetal force is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path. Isaac Newton described it as “a force by which bodies are drawn or impelled, or in any way tend, towards a point as to a centre”.