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Define the terms (i) 'cut-off voltage' and (ii) threshold frequency' in relation to the phenomenon of photoelectric effect. Using Einstein's photoelectric equation show how the cut-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 :(i) Cut-off voltage : The minimum negative potential (`V_(0)`) applied to the plate or anode (A) for which the photoelectric CURRENT just becomes zero. (II) Threshold frequency : The minimum frequency of incident radiation which is required to have photoelectrons emitted from a GIVEN metal surface. As per Einstein.s photoelectric equation `eV_(0)= vh-hv_(0)`, for `v gt v_(0)` `V_(0)=(h)/(e)(v-v_(0))` Hence the intercept, on the Y - axis, gives `v_(0)`. (ONE can READ `V_(0)` for any v, from the graph) 
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