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InterviewSolution
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Define the terms (i) 'cut-off voltage' and (ii) 'threshold frequency' in relation to phenomenon of photoelecric effect. Using Einstein's photoelectric equation show how the cutt-off voltage and threshold frequency for a given photosensitive material can be determined with the help of a suitable plot/graph. |
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Answer» Solution :2nd part: Einstein's equation: `eV_(0) = H (f-f_(0))` where, `V_(0)`= cut-off voltage due to frequency f of incident LIGHT, `f_(0)` = threshold frequency Now, `V_(0) = (hf)/(E) - (hf_(0))/(e)` This is of the form `y = mx + c`. So the graph of `V_(0)` vs f will be a STRAIGHT line AB of slope `(h)/(e)`. The point of intersection of AB with the f-axis given the value of `f_(0)`. For any incident frequency, corresponding to any point C on AB, the ordinate OD gives the value of the cut-off voltage `V_(0)`. 
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