Lesson 12

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MCAT_Retaker
Posts: 90
Joined: Thu Feb 01, 2018 3:58 am

Lesson 12

Post by MCAT_Retaker » Tue Jul 17, 2018 8:34 pm

Can you explain the relationship between magnetic field and electric field? i thought they are always perpendicular
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NS_Tutor_Alex
Posts: 36
Joined: Fri Jul 21, 2017 4:11 pm

Re: Lesson 12

Post by NS_Tutor_Alex » Thu Jul 19, 2018 8:55 pm

Hi MCAT_Retaker,

Great question! We want to be careful here because it's only the magnetic force that will travel perpendicularly to the magnetic field and that relationship is not the same for electric field and the resultant electric force. The goal of the question is to identify the direction of the magnetic field so that the test charge can move as shown in the question. This will only occur if the magnetic force is equal and opposite to the electric force. Because we need the magnetic force to point down in order to cancel the electric force out, the magnetic field must be pointing into or out of the page. The reason the magnetic field is into the page instead of coming out of the page is because our test charge is negative and not positive, thus we must reverse the direction found by using the right hand rule.

Hope that helps, if it's still a little hazy, the NextStep content review videos would be a fantastic resource to review!

Alex
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