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Thursday, January 27, 2011

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.