Difference between "Mass" "Matter" and "Energy"

Well the fancy of the subject "physics" is unexplainable. Understanding of basic terminology gives immense satisfaction. 

How many of you could differentiate the three terms "Matter", "Mass" & "Energy" which are essential for beginning understanding of physics? 

Let us start explaining things:- "Mass" is an attribute and not a physical thing. Mass is the attribute "inertia" of a physical object or of what ever is contained in a specified region of space. 

"Inertia" is the inherent reluctance to undergo a change in velocity. If one consults the research documents of decade 1900-10, when Einstein and others developed the equation E=mc2, one finds that for those physicists- the word "Mass" was synonym for "inertia". 

"Matter" is tangible stuff; What you can touch and sense with your hands and so a physical thing.Hence all matter has inertia and hence has mass. 

 "Energy" is the ability to do work. It is an attribute to physical object or of whatever is contained in a specified region of space. Three general forms for existence of energy are "Kinetic", "potential", "Radiant". "Kinetic" is the energy associated with motion. 

"Potential energy" is the energy that has potential for being converted to kinetic energy. 

"Radiant energy" is energy of Electromagnetic waves. 

Take a stone and throw into air. The stone which you are able to collect it from ground has got matter as you have touched and sensed it. While moving in air the stone doesn't get blown by wind breeze etc and does possess "inertia". It is moving with a velocity and does has Kinetic energy, at the same time it is at a varying height from ground and hence possess gravitational potential energy.Thus the stone in air has got partly kinetic energy and partly potential energy. Thus "mass' and "energy" exist as attributes of a physical system, just as do color or shape. Mass and energy exist in the same fashion and matter exists in different fashion. Hope this benefits the student community.......Have a nice day

How do we define Glass?

There are number of definitions of glass which have different approaches. 

There is no universally accepted or universal definition of glass. 

It is a fusion product of materials which have been cooled to a rigid condition with out crystallization(It need not be inorganic). 

Examples of familiar glasses made from cane sugar are lollipops and cotton candy. The former are in shape of rigid block and latter are flexible fibers.

Other definitions: 

1) An Amorphous solid or glass is one in which long range order is absent and the array of equilibrium atomic positions is strongly disordered. 

2) Glass is an uncrystallized solid material. 

3) Glass is an inorganic product of fusion which has been cooled to a rigid condition with out crystallizing. 

4) A general definition including all the aspects of glass is not possible; glass is to be conceived on one hand as a physical chemical condition and on other hand as a technical material.

Why to use Fuse?

Any electrical or electronic appliance is designed to take specified current. Under some circumstances, there may be drawing of larger currents by then then what they are rated for.

For instance too many appliances connected simultaneously in a circuit causing the total current drawn to be higher than can be handled by wires. This is called overloading.

The higher current due to short circuits or overloading can damage the appliances and the electric wires may even catch fire. To avoid this risk, a safety device called "Fuse" is used in series with the circuit.

A fuse is a short piece of wire of low melting point which is connected in series between Mains and the Appliance. When the current rises above the safe limit the fuse wire gets melted and makes the circuit open.

Design aspects of fuse like: Material of  wire, Dimensions etc are selected based on the safe limiting of current required.

                  

Electric power & Energy

Electric Power

Electric power is the electric work done per unit time.

1 Watt = 1 Joule / 1 Second

Though Watt is unit of power, it is too small for measuring domestic consumption of electricity. Thus we use a larger unit of power called Kilowatt.

Electrical Energy

It is usually measured in a unit called Kilowatt hour(KWh) which is amount of electrical energy consumed when an electrical appliance with a power rating of 1 KiloWatt is used for 1 hour.

1 KWh= 3.6 x 10 ^ 6 Joules

Power Rating of Domestic Appliances

The power rating of an electrical appliance tells us the rate at which the appliance uses electrical energy.
An electric iron box marked 220V, 1000W has a power consumption of 1000W at 220V AC, i.e it consumes electrical energy at the rate of 1000Joules per second when a potential difference of 220V is applied across it (which is potential difference at which electricity is supplied to our homes).  

The electrical energy consumed (in KWh) by an electrical appliance is given by the product of its power rating (in KW) and the time for which it is used(in hrs).

Slideshow on Radiation detectors given to GET 2012 batch.

GET 2012 batch can download the pdf file and can make any queries on subject in the comments box below.

Radiation detectors

View more presentations from Girishpalvai Kumar

How does a Light Emitting diode (LED) work?

Light Emitting Diode (LED) is always operated in forward bias mode.

Direct band semiconductors are used for LEDs.

Before applying voltage

After applying voltage

At sufficient voltage, electrons gain sufficient voltage so that they combine with holes to give light which has color that depends on energy gap of chosen semiconductor.

The wavelength of emitted light depends on energy gap and is expressed as 1.24 / Eg; where Eg is energy gap.