please explain and distinguish between emission and absorption spectra.and what is line spectra.........

shivani srivastva, 13 years ago

Grade:11

1 Answers

SAGAR SINGH - IIT DELHI

879 Points

13 years ago

Dear student,

Emission spectra:

When an element is heated strongly, or when a gas at low pressure is subjected to a high electric potential, the element begins to glow, indicating that it is emitting energy in the visible region of the spectrum. This arises from electrons that have absorbed a certain amount of energy and have been promoted to a higher energy state. When the electrons revert to a lower energy state, they lose energy by emitting photons whose energy corresponds to the energy loss, E. From Planck's law, E = hc/λ,

Absorption spectra:

The spectrum of white light shows an uninterrupted change in colour from red to violet, as shown above. In 1814, Fraunhofer, while repeating Newton's famous dispersion experiment using his own invention, the spectroscope, found that the spectrum of light from the sun showed a great many dark lines, which came to be known as "Fraunhofer lines".

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Sagar Singh

B.Tech, IIT Delhi