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P is It Always True that for Two Sources of Equal Intensity, the Number of Photons Emitted in a Given Time Are Equal? - Physics

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प्रश्न

Is it always true that for two sources of equal intensity, the number of photons emitted in a given time are equal?

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उत्तर

Let the source's area be A, and intensity of the source be I. The energy of each emitted photonis E. Then, the number of photons emitted in a given time will be `n = I/(AE)`

If the areas of the sources and the wavelengths of light emitted by the two sources are different, then the number of photons emitted will be different.

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  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 20: Photoelectric Effect and Wave-Particle Duality - Short Answers [पृष्ठ ३६३]

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एचसी वर्मा Concepts of Physics Vol. 2 [English] Class 11 and 12
अध्याय 20 Photoelectric Effect and Wave-Particle Duality
Short Answers | Q 2 | पृष्ठ ३६३

संबंधित प्रश्न

Monochromatic radiation of wavelength 640.2 nm (1 nm = 10−9 m) from a neon lamp irradiates photosensitive material made of caesium on tungsten. The stopping voltage is measured to be 0.54 V. The source is replaced by an iron source and its 427.2 nm line irradiates the same photo-cell. Predict the new stopping voltage.


A mercury lamp is a convenient source for studying frequency dependence of photoelectric emission, since it gives a number of spectral lines ranging from the UV to the red end of the visible spectrum. In our experiment with rubidium photo-cell, the following lines from a mercury source were used:

λ1 = 3650 Å, λ2 = 4047 Å, λ3 = 4358 Å, λ4 = 5461 Å, λ5 = 6907 Å,

The stopping voltages, respectively, were measured to be:

V01 = 1.28 V, V02 = 0.95 V, V03 = 0.74 V, V04 = 0.16 V, V05 = 0 V

Determine the value of Planck’s constant h, the threshold frequency and work function for the material.

[Note: You will notice that to get h from the data, you will need to know e (which you can take to be 1.6 × 10−19 C). Experiments of this kind on Na, Li, K, etc. were performed by Millikan, who, using his own value of e (from the oil-drop experiment) confirmed Einstein’s photoelectric equation and at the same time gave an independent estimate of the value of h.]


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