Threshold frequency of a metal is 5 × 10^ 13 ~s^ -1 upon which 1 × 10^ 14 ~s^ -1 frequency light is focused. Then the maximum kinetic energy of emitted electron is

Correct answer: B. 3.3 × 10^ -20 Following the conservation of energy principle, Kinetic energy ((1)/(2) m_e v^2)=h(v-v_0) =(6.626 × 10^ -34 ~J ~s)(1 × 10^ 14 ~s^ -1 -5 × 10^ 13 ~s^ -1 ) =(6.626 × 10^ -34 ~J ~s)(5 × 10^ 13 ~s^ -1 ) =3.313 × 10^ -20 ~J

AIIMS 2012

Exam: AIIMS
Year: 2012
Subject: Chemistry
Chapter: Structure of Atom

AIIMS 2012 · Chemistry · Structure of Atom

Threshold frequency of a metal is 5 × 10^ 13 ~s^ -1 upon which 1 ×...

Threshold frequency of a metal is

5 \times 10^{13} \mathrm{~s}^{-1}

upon which

1 \times 10^{14} \mathrm{~s}^{-1}

frequency light is focused. Then the maximum kinetic energy of emitted electron is

Options

A $3.3 \times 10^{-21}$
B $3.3 \times 10^{-20}$
C $6.6 \times 10^{-21}$
D $6.6 \times 10^{-20}$

Correct answer

B. $3.3 \times 10^{-20}$

Step-by-step solution

Following the conservation of energy principle, Kinetic energy

\left(\frac{1}{2} m_e v^2\right)=h\left(v-v_0\right) =\left(6.626 \times 10^{-34} \mathrm{~J} \mathrm{~s}\right)\left(1 \times 10^{14} \mathrm{~s}^{-1}-5 \times 10^{13} \mathrm{~s}^{-1}\right) =\left(6.626 \times 10^{-34} \mathrm{~J} \mathrm{~s}\right)\left(5 \times 10^{13} \mathrm{~s}^{-1}\right) =3.313 \times 10^{-20} \mathrm{~J}

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