As discussed in the A Closer Look box on 'Measurement and the Uncertainty Principle,' the essence of the uncertainty principle is that we can't make a measurement without disturbing the system that we are measuring. (a) Why can't we measure the position of a subatomic particle without disturbing it?

Video transcript

hey everyone in this example, we need to determine which of the given statements is correct. Based on the measurement and uncertainty principle statement A says that position and momentum of a particle can both be measured accurately. So before we can determine whether A is a correct statement, we want to recall that subatomic particles oops sub atomic particles are small and measured with light to find their position. So we can imagine our small photon particle. And if we visualize photons of light, which I'll just draw here being fired towards our particle, these photons are going to cause our particle to gain momentum and so are subatomic particle is now disturbed. And we would recall that the shorter the wavelength represented by lambda of our photon, we will have an increase in accuracy of our measurement of its position. The subatomic particles position. We would also understand that the greater the momentum of our particle that will correspond to a greater disturbance towards that particles position. So what we can say based off of what we've outlined below is that A is not going to be a correct statement. So let's move onto choice B. It says that one position of a particle is measured accurately. The momentum of a particle cannot be measured accurately. We would agree that this is a correct statement and that is due to the fact that as we've outlined before, we can't measure momentum of a particle at the same time measuring the position of our subatomic particle and that is due to the fact that we have such a great disturbance when it comes to the momentum of a particle being affected. That these two measurements, our position, our accuracy of our position of our particle particle can either only be measured first or we can just measure our momentum of a particle first. So it was it's either one or the other that we have to choose from and so B would definitely be a correct choice. So let's consider C. It says that the position and momentum of a particle cannot be measured accurately. We would rule that out because we can definitely pick one of them to measure accurately. And then lastly it says only the position of a particle can be measured accurately all the time. We know that both can be measured accurately. It's just that you have to choose one to measure first. So we would rule out D. And so the only correct choice to complete this example is choice B. If you have any questions, please leave them down below. Otherwise I'll see everyone in the next practice video.