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CBSE Class 12th Physics Notes: Dual Nature of Radiation and ...

Jan 19, 2017 ... CBSE class 12 chapter wise notes based on chapter 11, Dual Nature of Radiation and Matter, of class 12 NCERT Physics textbook are available in this article. ... Photoelectric Effect and Wave Theory of Light. Photon. Einstein's Photoelectric Equation: Energy Quantum of Radiation. Threshold frequency.

For more information, see CBSE Class 12th Physics Notes: Dual Nature of Radiation and ...

The difference between incident photon energy and the work function of the metal or material is the gain of kinetic energy of an electron, which can be expressed as follows

                     K.E = h\upsilon - \phi

                     Where, h - Planck's constant (6.626*10^{-34}),  \phi - work function, and \upsilon - frequency

        Relation between work function and threshold frequency

                     \phi = h \upsilon_o

                    Where, \upsilon_o - threshold frequency                  

Given that

Threshold frequency of the metal   \upsilon_o = 3.3* 10^{14} Hz

Frequency of light incident on the metal \upsilon = 8.2 * 10^{14} Hz

Step 1: Set up an equation for the cutoff voltage for the photoelectric emission

                     K.E = h\upsilon - \phi

                     K.E = h\upsilon - h \upsilon_o

                 According to the conversion law

                         K.E = eV

                       Where, charge of electron e = 1.6* 10^{-19} and V - potential difference(voltage)    

                         eV = h\upsilon - h \upsilon_o

                         V = \frac{ h(\upsilon - \upsilon_o)}{e}

Step 2: Plug in the given values in the above equation

                         V = \frac{h(\upsilon - \upsilon_o)}{e}

                         V = \frac{ 6.626 * 10^{-34} (8.2 * 10^{14} - 3.3* 10^{14})}{1.6* 10^{-19}}

                          V = 2.0292 volts

                Therefore, the cutoff voltage for the photoelectric emission     V = 2.0292 volts