Photoelectric Effect -03- Stopping Potential

Rebiaz Studio

A photoelectron moves at a speed of 1.35x10⁶ m/s. What is the stopping potential?  Watch videos related to MODERN PHYSICS: https://dailymotion.com/playlist/x90qrm

Transcript

00:00Dear friends, be persistent, patient, and never give up in learning.

00:08The photoelectron in the photoelectric effect experiment moves in a straight line at a constant speed.

00:15Now, we are asked to calculate the stopping potential of the electron.

00:22In the problem sheet, we see the values for the electron's velocity, electron's mass, and electron's charge.

00:30The image on the monitor screen is the apparatus for conducting the photoelectric effect experiment.

00:39There are two conducting plates inside a vacuum tube.

00:45Both plates are connected to a battery.

00:50When viewed from the battery's poles, the left plate will be positively charged, and the right plate will be negatively charged.

00:57A beam of light is directed toward the left plate.

01:04Immediately after absorbing a photon, an electron from the left plate will move toward the right plate.

01:10This is the photoelectron.

01:16The photoelectron moves with an initial velocity V to the right.

01:20Observe closely.

01:25The electron is a negatively charged particle.

01:28The left plate, on the other hand, is positively charged.

01:33According to Coulomb's law, negative charges are attracted to positive charges.

01:40The electron moves to the right, but the Coulomb force is to the left.

01:44The velocity and force are in opposite directions.

01:49This means the electron will slow down to the right.

01:54The stopping potential is the voltage between the two poles that must be applied so that the photoelectron enters the right plate.

02:01Then, the electron moves back to the left toward the positively charged plate.

02:11So, there are two important points here.

02:14The first point is located at the positive pole.

02:18The second point is at the negative pole.

02:20Because energy is conserved, the energy at point 1 is the same as the energy at point 2.

02:31At point 1, the electron has kinetic energy.

02:35However, the electron is still attached to the positive pole.

02:42At point 2, the electron stops moving, but it has electrical potential energy.

02:46Half mv squared is equal to ev0.

02:53The value of v0 is the stopping potential.

02:59Some of these values are known.

03:04This is where the calculator comes in.

03:07V0 is approximately 5.2 volts.

03:11This is the answer to this question.

03:13Happy learning, everyone.

Category

Transcript

Be the first to comment

Recommended