Need help for Physics

4

Hi. I'm making some notes, preparing for my Jan 25 IAL Unit 4 Physics Paper.

I need to know weather F=BQv is the same as F=Bev.
From what i know, Q is the particle charge and e is electron charge?
Please correct me if am wrong. And also, I've seen these 2 equations being used in different places (like F=Bev is being used to turn into r=p/Be)
Please explain it to me because I don't quite understand it.

Thank you very much!!!

Reply 1

helloos

6

depends on the context, if the question is about an electron in a magnetic field, both are interchangeable, youll just sub Q as e. Otherwise, i think F=BQv is a more accurate formula, as Q could be multiple electrons/protons. F=Bev turning into r=p/Be is a combination of topics, circular motion and magnetic field, like how gravitational field and circular motion are related.

hope i didnt confuse u further 🥲

Reply 2

jia_jie0728

OP

4

Original post

by helloos

depends on the context, if the question is about an electron in a magnetic field, both are interchangeable, youll just sub Q as e. Otherwise, i think F=BQv is a more accurate formula, as Q could be multiple electrons/protons. F=Bev turning into r=p/Be is a combination of topics, circular motion and magnetic field, like how gravitational field and circular motion are related.
hope i didnt confuse u further 🥲

Hi. Don't worry, thats a wonderful explanation.

In what situation will I use F=Bev? I'm pretty sure most of the time I'll be using F=BQv right? I mean Q can be electron charge as well so the answer will still be correct if I keep the values right.

Thank you!

Reply 3

helloos

6

hi sorry, i think i was a little unclear in the prev post. by interchangeable i meant ull get the same final ans. F=Bev is not an actual formula but a substituted one so you shld be only be using F=BQv then sub in the values of Q.
sorry for the confusion!

Reply 4

jia_jie0728

OP

4

Original post

by helloos

hi sorry, i think i was a little unclear in the prev post. by interchangeable i meant ull get the same final ans. F=Bev is not an actual formula but a substituted one so you shld be only be using F=BQv then sub in the values of Q.
sorry for the confusion!

Sorry for the late reply. I understand it now. Thank you so much for the explanation!!

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