# Physics EE mass of an electron Help

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Hey all,

So I am doing my extended essay in Physics. I completed the experiment in my first year of IB and wrote about the method and theory as well. I have a few days left of vacations and I decided to continue working on it.

Originally my experiment was about finding the mass of an electron. This consists of

1. finding the e/m ratio (charge to mass ratio) of an electron. This I have done and I have all the collected data. Basically there is an electron gun between two magnetic coils, centripetal force acts and the beam moves in a circle.

2. Milikan experiment to find the charge of an electron. This I left out as my supervisor advised that it would be too lengthy and its hard to get accurate results.

The problem is my approach to the ee doesn't have an explicit "research" element. In the ee guide research questions are about how one thing affects another or the relationship between a dependent variable and an independent variable. Like how does the temperature of a medium affect the speed of sound, or how does the viscosity of a medium affect terminal velocity. In my case the only variable I have is the radius of the electron beam formed. So the only RQ I can come up with is :

How does the magnitude of the magnetic field and accelerating voltage affect the path of an electron moving through a magnetic field?

However I fear this is too trivial (the stronger the field the smaller the radius) and it does not incorporate the e/m thing and the mass of an electron. My supervisor said that as long as there is a relationship between two variables it should not be a problem. I will discuss this again with my supervisor when school starts but as for now I want to know someone else's opinion.

Any ideas?

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A good topic does not need to be split into 2 questions. The topic should be partially driven by concepts presented in class. The question you are attempting to answer (#1) is trivial: equating centripetal force and magnetic force. In fact it would be difficult to experimentally derive the relationship without knowing the answer. Avoid topics that can easily be exam questions. The Millikan experiment is definitely on the right track but it requires more precise instruments than typically found in a high school. With that said, variants upon the Millikan experiment are perfectly valid even though they do not explicitly explore a relationship. I would suggest that you ask for high-scoring topics from previous years and to find inspirations.

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On 8/3/2017 at 7:32 AM, kw0573 said:

A good topic does not need to be split into 2 questions. The topic should be partially driven by concepts presented in class. The question you are attempting to answer (#1) is trivial: equating centripetal force and magnetic force. In fact it would be difficult to experimentally derive the relationship without knowing the answer. Avoid topics that can easily be exam questions. The Millikan experiment is definitely on the right track but it requires more precise instruments than typically found in a high school. With that said, variants upon the Millikan experiment are perfectly valid even though they do not explicitly explore a relationship. I would suggest that you ask for high-scoring topics from previous years and to find inspirations.

Thank you for your thorough reply, I will have a discussion with my supervisor as soon as I can and discuss this.

What exactly do you mean by variants to the Milikan experiment? Also how do you formulate a research question if there is no apparent relationship?

p.s. I don't suppose you have example EEs from 2015 onwards. All the ones I find online are very old.

Edited by HKamal

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4 hours ago, HKamal said:

Thank you for your thorough reply, I will have a discussion with my supervisor as soon as I can and discuss this.

What exactly do you mean by variants to the Milikan experiment? Also how do you formulate a research question if there is no apparent relationship?

p.s. I don't suppose you have example EEs from 2015 onwards. All the ones I find online are very old.

Variants I meant instead of finding a charge of 1 electron, maybe people want to find charge of alpha particles, atomic ions, etc.

The EE requirements were updated (see our Files section) for people graduating in 2018 but the general expectations are more or less similar. Any good EE example will do.

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