Exam-style question
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What is the minimum frequency required to ionize an atom with a work function of 4 eV?.
- A.1.0 x 10^15 Hz
- B.1.5 x 10^15 Hz
- C.2.0 x 10^15 Hz
- D.3.0 x 10^15 Hz
Model answer
What a good answer should say
- 1.0 x 10^15 Hz
Explanation
Why this works
The minimum frequency (f) required to ionize an atom can be calculated using the formula E = hf, where h is Planck's constant (6.63 x 10^-34 J·s). First, convert the work function from eV to joules: 4 eV = 4 x 1.6 x 10^-19 J = 6.4 x 10^-19 J.
Now, rearranging gives f = E/h = (6.4 x 10^-19 J) / (6.63 x 10^-34 J·s) = 9.65 x 10^15 Hz, which rounds to approximately 1.0 x 10^15 Hz. Thus, the minimum frequency is 1.0 x 10^15 Hz.
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