Photoelectric Effect -04- Threshold Frequency

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The work function of a metal plate is 3.97x10⁻¹⁹ Joules. What is the threshold frequency of the plate?  Watch videos related to MODERN PHYSICS: https://dailymotion.com/playlist/x90qrm

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00:00Hi friends, study hard, because nothing you do is wasted.

00:07A metal has a specific work function.

00:12Now, we're asked to calculate the threshold frequency of that metal.

00:19Of course, the work function and Planck's constant are listed on the worksheet.

00:27Before we go any further, write down some of the values listed on the worksheet.

00:34The units for each quantity are in the international system of units.

00:38Just leave them as they are.

00:43As a refresher, this is a metal plate.

00:49On the surface of this metal there are several electrons.

00:54Light is composed of several rays of light at various frequencies.

01:00However, not all frequencies can be absorbed by electrons or cause electrons to be excited from the metal surface.

01:09After electrons are excited, they may remain stationary on the metal surface, or they may move at a certain speed.

01:19The frequency that causes electrons to be excited exactly to a relative standstill is the threshold frequency.

01:29If we look more closely, why are electrons in the electron cloud?

01:35The electron is bound to the atomic nucleus.

01:40The binding force between the electron and the atomic nucleus is equal to the work function, Φ.

01:47The photon energy is Hf.

01:52So Φ is equal to Hf.

01:56To differentiate, we can add a subscript 0 to F to identify the threshold frequency.

02:04We already know the values of the Planck constant and the work function.

02:10A little calculation reveals that F0 is equal to 6 times 10 to the power of 14 Hz.

02:17This is the threshold frequency of the metal.

02:21Happy learning, everyone!

02:22Happy learning, everyone!

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