SSC Examination Result 2013

lesson for science group

Chapter 1 Physics & TEST Conceptual Premises:

Mastering Units:

(si) units:

·         The SI Unit is considered an internationally accepted unit of measurement. To be more accurate, it is considered a unit adopted for international use under the Système International d'Unités in science and technology. The seven fundamental units are the meter, kilogram, second, ampere, kelvin, candela, and mole.

·         Meter: is denoted by symbol m which is the measure of distance / displacement.

·         Second: is 60th of minute or a unit of time that is equal to 1/60th of a minute and its symbol is s.

·         Kg or kilogram is the measurement of mass and denoted by symbol kg.

·         Ampere: is SI unit of electric current: the basic unit of electric current in the SI system, equal to a current that produces a force of 2x10-7 newton's per meter between two parallel conductors in a vacuum. Its symbol is A.

·         Degrees kelvin: is a unit of temperature measurement. When we take a close look on this, we come to know that it is the unit of absolute temperature i.e. the SI unit of absolute temperature, equal to 1/273.16 of the absolute temperature of the triple point of water, equivalent to one degree Celsius. A temperature in kelvin may be converted to Celsius by subtracting 273.16.its symbol is K.

·         There are also some complex items that are included in this category such as velocity and acceleration. Velocity represents the rate of change in position i.e. the rate of change in the position of an object as it moves in a particular direction. And acceleration denotes the measure of increase in velocity i.e. a measure of the rate of increase in the velocity of something per unit of time.

·         Few things are generally expressed in derivatives that represent the change of function or the limit approached in the ratio of a function and its variable, as the variable is changed ever more infinitesimally. For example, in physics, Force is generally represented by symbol F and considered as influence that moves something i.e. a physical influence that tends to change the position of an object with mass, equal to the rate of change in momentum of the object. But for convenience, its normally measured in the derivative unit Newton N Where few important derivatives are also shown in the following table as well.

·         Newton is the term that is used to describe the unit of force. To be more accurate, it is considered an SI unit of force equivalent to the force that produces an acceleration of one meter per second per second on a mass of one kilogram. Symbol is N.

·         Energy is described in physics as capacity to do work: the capacity of a body or system to do work. Symbol is E. and Joule is unit of energy or the International System unit of energy or work, equal to the work done when the application point of a one newton force moves one meter in the direction of application. Symbol is J.

·         The Power is described as the measure of rate of doing work. It is in fact the measure of the rate of doing work or transferring energy, usually expressed in terms of wattage or horsepower. Symbol is P. and Watt is the unit of electrical power especially the international SI unit of power equal to the power produced by a current of one ampere acting across a potential difference of one volt. Symbol is W.

·         The Charge is referred as electric property of matter or a fundamental characteristic of matter, responsible for all electric and electromotive forces, expressed in two forms known as positive and negative. Charge is also referred in physics as an excess or lack of electrons or a quantity of electricity caused by an excess or lack of electrons. And coulomb is referred as a unit of electric charge or the SI unit of electric charge equal to the amount of charge transported by a current of one ampere in one second. Symbol is C.

·         The Potential is referred as the work required to move an electric charge. It is in fact the work required to bring a unit of positive electric charge from infinity to a specific point in an electric field. Symbol is V. and Volt is described as unit of electric potential difference. In other words the unit of electromotive force and electric potential difference equal to the difference between two points in a circuit carrying one ampere of current and dissipating one watt of power. Symbol is V.

·         The Resistance can be described in many ways. It is described as the force opposing another force: a force that opposes or slows down another force with Symbol Rr. It can be described as opposition to electric current or the opposition that a circuit, component, or substance presents to the flow of electricity with Symbol R. It is also written as source of resistance or something that is a source of opposition to the flow of electricity, e.g. a resistor with Symbol R. and Ohm is the unit of electrical resistance. It is indeed the SI unit of electrical resistance, equal to the resistance between two points on a conductor when a potential difference of 1 volt produces a current of 1 ampere. Symbol is Ω.

·         The Capacitance is termed as ability to store electric charge or the ability of a substance to store an electric charge. You can describe it as the ability of component to store charge especially the ability of an electronic component to store an electric charge. It is in fact the measure of electric charge storage i.e. a measure of the capacitance of a substance, equal to the surface charge divided by the electric potential. Symbol is C. and Farad is the unit of electrical capacitance. It is in fact the SI unit of capacitance equal to that of a capacitor carrying one coulomb of charge when a potential difference of one volt is applied. Symbol is F.

·         The Magnetic Field is defined as the magnetized region of space especially a region of space surrounding a magnetized body or current-carrying circuit in which the resulting magnetic force can be detected. And Tesla is termed as the unit of magnetic flux density. It is in fact the derived unit of magnetic flux density in the SI system, equal to a flux of one weber in an area of one square meter. Symbol is T. it is worth mentioning here that magnetic flux density is the strength of magnetic field in medium or the strength of a magnetic field multiplied by the porosity of a medium, measured in teslas or gauss. Symbol is B.