How can I find "dx" in a straight line of electric charge?(Picture)

  • Thread starter MatinSAR
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  • #1
MatinSAR
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Homework Statement:
How can I find "dx" in a straight line of electric charge?(Details in Picture)
Relevant Equations:
r=R/cos(teta)
x=rtan(teta)
1646478251956.png

This is the question ... I have it's solution ...
1646478322100.png

1646478364142.png



My problem : I can't understand why dx=R/cos^2(teta) dteta
I have thought many hours but I couldn't find it's reason ... Can anyone please help with this ?!
 

Answers and Replies

  • #2
ergospherical
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1,214
If ##x = R\tan{\theta}##, then ##dx/d\theta= \dots##
 
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  • #3
MatinSAR
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37
If ##x = R\tan{\theta}##, then ##dx/d\theta= \dots##
I got it ... I have learned this in a wrong way but now I know what was wrong ... Thanks a lot 🌷
 
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