Why do mirrors show left as right and not top as bottom?

It is a misconception that most of the students pose the question as above.

Mirror only shows the reflected image of the object before it. 

This is more confused when we think of example of ourselves

standing before the mirror. It is the bi-symmetry of the human being which is exactly reflected in mirror as our left being right and right being left. Hence we get confused with it. To be more clear the light reflected from our left side will be falling on the mirror's right side relatively.Where as reflected light from top falls on the top side of mirror and from bottom falls on mirror's bottom side. Hence we see that top is not reversed to bottom.

   

 

Fukushima reactor blast in Japan

Japan suffered disaster aftermath of the destruction made by Tsunami due to failure of its Nuclear reactors.

The failure of cooling system is the reason for explosions in the reactors. We know that the enormous heat generated during fission process is compensated by coolant under flow in reactors.

The failure of cooling system called as Loss of coolant accident would lead to severe effects in reactor. Even after shutdown there is decay heat which shall be cooled to protect the core of the reactor.

In failure of this the pressure inside the core may increase by many folds and result in blast. The consequence is the escape of radioactive gases containing traces of Iodine, Cesium-137 etc which pose serious threat to health of people in the vicinity of reactor.

Already it is announced that the natural background in Japan is increased by many folds giving us a serious alarm..

Technology is evidently a best resource for development but at the same time periodic review is must to tackle such disasters.

Hopefully the entire world would wake up to improve the existing system of technology for eliminating such disasters in the future.  
 



 

Internal energy

Two solid copper spheres, having different radii, undergo the same temperature change. A student states that the change in internal energy of the two objects would be the same. Briefly discuss this statement.

Internal energy  is the stored energy and is not apparently shown by any system. The energy is possessed by the system due to its molecular constitution and the position of atoms/molecules. In the above query, though the sizes are different the change in temperature is uniform and the change in energy at atomic/molecular level is same and hence the change in internal energy would be same. This is because the atomic structure is same in both cases.
So effect of temperature is same in both cases. 

Speed of Light faster than sound

Sound is generated due to vibrations in atoms/molecules in a medium and thus always require materialistic medium. The physical parameters like Temperature, Pressure etc., effects the sound velocity.

On the other hand Light doesn't require a materialistic medium. It transmits in space through field.

The concept of field is still a mysterious thing to explain meticulously.

Light is transmitted by 'photons' which are treated as zero mass entity. The speed of sound is negligible when compared to speed of light. This is one of the reasons that while thunderbolts, we see flashing light fast and then hear sound. This is a best example.

In fact light falls in different spectrums and light which gets generated at a point travels through the universe changing its presence int he spectrum.