Units and Dimensions

1. The amount of a substance that contains as many atoms, molecules, ions, or other elementary units as the number of atoms in 0.012 kilogram of carbon 12.

2.  The SI unit of force is newton . A force of one newton will accelerate a mass of one kilogram at the rate of one meter per second per second.

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2  1 kWh is the amount of electrical energy consumed in 1 hour when the rate of consumption is 1000Joules/second

4, The SI unit of electric current

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2 impulse = F*t (force multiplied by time)

1 The candela is defined to be the luminous intensity of a light source producing single-frequency light at a frequency of 540 terahertz (THz) with a power of 1/683 watt per steradian, or 18.3988 milliwatts over a complete sphere cantered at the light source.

1  the SI unit of work or energy is Joule (J), defined to be the work done by a force of one newton acting to move an object through a distance of one meter in the direction in which the force is applied.

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3 The distance that light travels in a vacuum in one year, approximately 9.46 trillion (9.46 × 1012) kilometers or 5.88 trillion (5.88 × 1012) miles.

4      1 kWh = 1 kilowatt per hour

4   1 volt is equal to the difference of electric potential between two points on a conducting wire carrying a constant current of one ampere when the power dissipated between the points is one watt. Clearly it cannot be a basic unit

4    To measure the fundamental physical quantities Length, Mass and time we have three systems of units, they are (i) C.G.S System (ii)F.P.S System and (iii)M.K.S System. In all these three systems only three physical quantities length, mass and time are considered to be fundamental quantities.But, in systems International (S.I) system there are seven fundamental physical quantities. Which are (i) Length( ii) Mass( iii) Time (iv) Electric current (v) Thermo dynamic temperature (vi) Luminous intensity( vii) Quantity of substance.

4   One tesla is defined as the field intensity generating one newton of force per ampere of current per meter of conductor. Equivalently, one tesla represents a magnetic flux density of one weber per square meter of area.

3   Inertia is the resistance of mass

4    The ratio of the magnetization of a material to the magnetic field strength is called magnetic susceptibility; it is a tensor when these two quantities are not parallel; otherwise it is a simple number. Poisson ratio is a ratio i.e. a number ( Number is a unit less thing)

2      It is defined as the rate of change of angular displacement with respect to time. Angular velocity can be expressed in degrees per unit time (second, minute, hour, etc.), radians per unit time, or even revolutions per unit time.

1    dyne is the CGS unit of force, Definition: it is the force which accelerates a mass of one gram at the rate of one centimetre per second .

3   Luminance is the luminous intensity of a surface, measuring the intensity of the light emitted (or reflected) in all directions per unit of area of the surface. One Lambert is the luminance of a surface that emits or reflects one lumen per square centimetre.

3      the CGS unit of magnetic flux density is gauss This exerts a force of 0.1 dyne per ampere on a current-carrying conductor placed in the field.

3   The CGS unit of heat energy is cal. The amount of heat required at a pressure of one atmosphere to raise the temperature of one gram of water by one degree Celsius.

1        The newton, is the force which accelerates a mass of one kilogram at the rate of one meter per second . The ratio between a CGS unit and the corresponding MKS unit is usually a power of 10. A newton accelerates a mass 1000 times greater than a dyne does, and it does so at a rate 100 times greater, so there are 100 000 = 105 dynes in a newton.

2   The SI unit of magnetic flux is weber . Flux is the rate (per unit of time) at which something crosses a surface perpendicular to the flow. If the something is a magnetic field, then the magnetic flux across a perpendicular surface is the product of the magnetic flux density.

3   There are seven base SI units (for mass, length, time, electric current, temperature, luminous intensity, and amount of substance) from which the other units may be derived.