Roboguru

Kecepatan elektron yang keluar dari suatu logam ketika diberi cahaya berfrekuensi  adalah . Berapakah kecepatan elektron yang keluar jika logam disinari cahaya yang berfrekuensi ?

Pertanyaan

Kecepatan elektron yang keluar dari suatu logam ketika diberi cahaya berfrekuensi begin mathsize 14px style 1 comma 5 cross times 10 to the power of 15 space Hz end style adalah begin mathsize 14px style 6 cross times 10 to the power of 5 space straight m divided by straight s end style. Berapakah kecepatan elektron yang keluar jika logam disinari cahaya yang berfrekuensi begin mathsize 14px style 3 cross times 10 to the power of 15 space Hz end style?

Pembahasan Soal:

Soal ini dapat dikerjakan menggunakan persamaan efek fotolistrik.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell E K end cell equals cell E minus E subscript 0 end cell row cell 1 half m subscript e v squared end cell equals cell h open parentheses f minus f subscript 0 close parentheses end cell row cell f subscript 0 end cell equals cell f minus fraction numerator 1 half m subscript e v squared over denominator h end fraction end cell row blank equals cell 1 comma 5 cross times 10 to the power of 15 minus fraction numerator begin display style 1 half end style cross times 9 comma 1 cross times 10 to the power of negative 31 end exponent cross times open parentheses 6 cross times 10 to the power of 5 close parentheses squared over denominator 6 comma 625 cross times 10 to the power of negative 34 end exponent end fraction end cell row blank equals cell 1 comma 5 cross times 10 to the power of 15 minus fraction numerator begin display style 163 comma 8 cross times 10 to the power of negative 21 end exponent end style over denominator 6 comma 625 cross times 10 to the power of negative 34 end exponent end fraction end cell row blank equals cell 1 comma 5 cross times 10 to the power of 15 minus 0 comma 25 cross times 10 to the power of 15 end cell row blank equals cell 1 comma 25 cross times 10 to the power of 15 space Hz end cell end table end style 

Karena memakai logam yang sama maka;

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell E K end cell equals cell E minus E subscript 0 end cell row cell 1 half m subscript e v squared end cell equals cell h left parenthesis f minus f subscript 0 right parenthesis end cell row cell v squared end cell equals cell fraction numerator h left parenthesis f minus f subscript 0 right parenthesis over denominator 1 half m subscript e end fraction end cell row cell v squared end cell equals cell fraction numerator 6 comma 625 cross times 10 to the power of negative 34 end exponent left parenthesis 3 cross times 10 to the power of 15 minus 1 comma 25 cross times 10 to the power of 15 right parenthesis over denominator 1 half cross times 9 comma 1 cross times 10 to the power of negative 31 end exponent end fraction end cell row blank equals cell fraction numerator 11 comma 59375 cross times 10 to the power of negative 19 end exponent over denominator 4 comma 55 cross times 10 to the power of negative 31 end exponent end fraction end cell row v equals cell square root of 2 comma 548 cross times 10 to the power of 12 end root end cell row blank equals cell 1 comma 595 cross times 10 to the power of 6 space straight m divided by straight s end cell end table end style 

Dengan demikian, kecepatan elektron yang keluar dari logam adalah begin mathsize 14px style 1 comma 595 cross times 10 to the power of 6 space straight m divided by straight s end style.

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 12 Maret 2021

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