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What are Fraunhofer lines? How are they useful in the identification of elements present in the Sun? - Physics

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प्रश्न

What are Fraunhofer lines? How are they useful in the identification of elements present in the Sun?

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उत्तर

When the spectrum obtained from the Sun is examined, it consists of a large number of dark lines (line absorption spectrum). These dark lines in the solar spectrum are known as Fraunhofer lines.

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अध्याय 5: Electromagnetic waves - Evaluation [पृष्ठ २८३]

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सामाचीर कलवी Physics - Volume 1 and 2 [English] Class 12 TN Board
अध्याय 5 Electromagnetic waves
Evaluation | Q II. 6. | पृष्ठ २८३

संबंधित प्रश्न

Do electromagnetic waves carry energy and momentum ?


Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor

(a) increases
(b) decreases
(c) does not change
(d) is zero


Consider the situation of the previous problem. Define displacement resistance Rd = V/idof the space between the plates, where V is the potential difference between the plates and id is the displacement current. Show that Rd varies with time as `R_d = R(e^(t"/"tau) - 1)` .


The energy associated with light of which of the following colours is minimum : 


Which of the following is false for electromagnetic waves.


If the magnetic monopole exists, then which of the Maxwell’s equation to be modified?


Let E = E0 sin[106 x -ωt] be the electric field of plane electromagnetic wave, the value of ω is ______.


A plane EM wave travelling along z direction is described by `E = E_0 sin (kz - ωt)hati` and `B = B_0 sin (kz - ωt)hatj`. show that 

  1. The average energy density of the wave is given by `u_(av) = 1/4 ε_0E_0^2 + 1/4 B_0^2/mu_0`.
  2. The time averaged intensity of the wave is given by `I_(av) = 1/2 cε_0 E_0^2`.

Sunlight falls normally on a surface of area 36 cm2 and exerts an average force of 7.2 × 10-9 N within a time period of 20 minutes. Considering a case of complete absorption the energy flux of incident light is ______.


An electromagnetic wave of frequency 3 GHz enters a dielectric medium of relative electric permittivity 2.25 from vacuum. The wavelength of this wave in that medium will be ______ × 10-2 cm. 


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