Magnetic Fields. Finding the angle of a moving charge.

zeldajae
Messages
8
Reaction score
0

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:
Physics news on Phys.org
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!
 

Thread 'Direction of the magnetic field of an oscillating charge'

Hello everyone, I’m considering a point charge q that oscillates harmonically about the origin along the z-axis, e.g. $$z_{q}(t)= A\sin(wt)$$ In a strongly simplified / quasi-instantaneous approximation I ignore retardation and take the electric field at the position ##r=(x,y,z)## simply to be the “Coulomb field at the charge’s instantaneous position”: $$E(r,t)=\frac{q}{4\pi\varepsilon_{0}}\frac{r-r_{q}(t)}{||r-r_{q}(t)||^{3}}$$ with $$r_{q}(t)=(0,0,z_{q}(t))$$ (I’m aware this isn’t...
View full post »

Thread 'Initial conditions for orbits around a wormhole'

Hi, I had an exam and I completely messed up a problem. Especially one part which was necessary for the rest of the problem. Basically, I have a wormhole metric: $$(ds)^2 = -(dt)^2 + (dr)^2 + (r^2 + b^2)( (d\theta)^2 + sin^2 \theta (d\phi)^2 )$$ Where ##b=1## with an orbit only in the equatorial plane. We also know from the question that the orbit must satisfy this relationship: $$\varepsilon = \frac{1}{2} (\frac{dr}{d\tau})^2 + V_{eff}(r)$$ Ultimately, I was tasked to find the initial...
View full post »

Similar threads

Direction of the magnetic field of an oscillating charge
Replies
1
Views
157
Find the field inside and outside a spherical geometry
Replies
2
Views
2K
A Magnetic field produced by moving charge in operator form
Replies
14
Views
1K
I Charge movement relative to magnetic field frame dependence/invariance
Replies
5
Views
936
Lagarangian of a charged particle in a magnetic field (magnetic monopole)
Replies
4
Views
2K
Torque on a Circular Current Loop under a Misaligned Magnetic Field
Replies
1
Views
1K
Special relativity - angles between fields
Replies
1
Views
1K
Electron moving toward an magnetic field
Replies
1
Views
2K
Finding Velocity and angle for magnetic field
Replies
4
Views
2K
Do Moving Charges Create or Induce Magnetic Fields?
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top