Question

The threshold frequency for a photo-sensitive metal is 3.3 x 10¹⁴ Hz. If light of frequency 8.2 x 10¹⁴ Hz is incident on this metal, the cut -off voltage for the photo-electric emission is nearly

2 V

3 V

5 V

1 V

Name: Wired Faculty - The Best Learning App
Rating: 4.6 (1864 reviews)

Solution

2 V

straight V subscript straight o space equals space fraction numerator straight E minus straight V over denominator straight e end fraction space equals space fraction numerator straight h space left parenthesis straight v minus straight v subscript straight o right parenthesis over denominator straight e end fraction space equals fraction numerator space 6.62 space straight x space 10 to the power of negative 34 end exponent space left parenthesis 8.2 space straight x space 10 to the power of 14 minus 3.3 space straight x space 10 to the power of 14 right parenthesis over denominator 1.6 space straight x space 10 to the power of negative 19 end exponent end fraction equals space fraction numerator 6.62 space straight x space 10 to the power of negative 34 end exponent over denominator 1.6 end fraction space straight x space 4.9 space straight x space 10 to the power of 33 space equals space fraction numerator 6.62 space straight x space 4.9 space straight x space 10 to the power of negative 1 end exponent over denominator 1.6 end fraction equals space straight V subscript straight o space equals space 2 space volt

straight V subscript straight o space equals space fraction numerator straight E minus straight V over denominator straight e end fraction equals space fraction numerator straight h space left parenthesis straight v minus straight v subscript straight o right parenthesis over denominator straight e end fraction equals space fraction numerator 6.62 space straight x space 10 to the power of negative 34 end exponent space left parenthesis 8.2 space straight x space 10 to the power of 14 right parenthesis minus 3.3 space straight x space 10 to the power of 14 over denominator 1.6 space straight x space 10 to the power of negative 19 end exponent end fraction equals space fraction numerator 6.62 space straight x space 10 to the power of negative 34 end exponent space straight x space 4.9 space straight x space 10 to the power of 33 over denominator 1.6 end fraction equals space fraction numerator 6.62 space straight x space 4.9 space straight x space 10 to the power of negative 1 end exponent over denominator 1.6 end fraction equals space straight v subscript straight o space equals space 2 space volt

For Daily Free Study Material Join wiredfaculty