Magnetic Fields. Finding the angle of a moving charge.

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SUMMARY

The discussion focuses on calculating the angle θ between the velocity of an electron and a magnetic field with a magnitude of 8.70 X 10-4 T. The user initially miscalculated the force due to using the incorrect mass of the electron, stating it as 1.673 X 10-27 kg instead of the correct value of 9.1 X 10-31 kg. After correcting this error, the user successfully calculated the angle θ to be 19.7 degrees, aligning with the textbook answer.

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  • Review the Lorentz force equation and its applications in electromagnetic fields.
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  • Practice solving problems involving forces on charged particles in magnetic fields.
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zeldajae
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Homework Statement



An electron is moving through a magnetic field whose magnitude is 8.70 X 10-4 T. The electron experiances only a magnetic force and has an acceleration of magnitude 3.50 X 1014 m/s2. At a certain instant, it has a speed of 6.80 X 106 m/s. Determine the angle \theta (less than 90o) between the electron's velocity and the magnetic field.

Homework Equations



F=ma

B = F / qo v (sin\theta)

The Attempt at a Solution



We know the mass of the electron= 1.673 X 10-27
So we plug that in the equation F=ma=(1.673 X 10-27)(3.5 X 1014 m/s2=5.86 X 10-13

Then we use the magnetic field equation and solve for sin\theta

sin\theta = F / q v B = (5.86 x 10-13)/((8.7 X 10-4)(6.8 X 106)(1.6 X 10-19)) = 618.608

That is wrong because the books answer is 19.7o. I know I am supposed to take inverse of the answer to find the angle. But I did my calculation correct and I am still getting the same answer...is there anything that I am doing wrong? Thanks
 
Last edited:
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zeldajae said:
We know the mass of the electron= 1.673 X 10-27

Really?!:wink:
 
gabbagabbahey said:
Really?!:wink:

Sorry, The mass of an electron is 9.1 X 10-31

After all the calculation, I get the right answer! Thanks for letting me know! I did a silly mistake!
 

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