[Solved] EM fields Homework help!  



Can anyone help with Question 7(a)(ii) ? 


Use F=EQ, you have Q and can find E by first

Use Work Done (given as the question as change in KE) =QV to get potential difference,


Then put that into E=V/d (again given in the question) to get E. Then you can use F=EQ

"Either this wallpaper goes, or I go"- Oscar Wilde's last words

The question after asks for the electric field, so she doesn't even have to work that out yet! just using W=Fd is so much simpler!


I think your problem is you're thinking in terms of magnetic fields (you wrote down F=Bqv). Whereas in fact you have a uniform electric field. 

In this case all you have to use is work done = Fd

You know the work done on the particle is going to cause the increase in KE mentioned in the question (4x10^-16 J) so this is going to be equal to the Force we are looking for multiplied by the distace they give us (63mm). 


PlanckTime - Amin


Thank you!

No problemo @saeed and I are always willing to help!


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