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SI123
The electric field between the 2 parallel plates of an oscilloscope is 1.2 x 10^5 V/m. If an electron of energy 2 keV enters at right angles to the field, what will be its deflection if the plates are 1.5 cm long?
The deflection angle is required?
deflection angle is not mentioned in the book
then what is asked? what you mean find deflection??
|dw:1361792988295:dw| Y is the deflection that has to be calculated
|dw:1361855358005:dw|for angles 180=x+y+z
oh 45 is the other number it could be
in this case, since it is constant, uniform acceleration due to the electric field, by Newton's second law, \(\Sigma \vec F= q \vec E = m \vec a\) where q and m of the electron are known constants. so, \(\vec a=\frac{q \vec E}{m}\), which will be different in direction of the electric field, as expected, now, the original speed of the electron can be calculated from: \(\frac{1}{2}mu^2= 2KeV\), so \(u=\sqrt{ \frac{4KeV}{m}}\) by the equations of motion, \(\vec S_x=\vec u_x t + \frac{1}{2} \vec a_x t^2\), but \(\vec u_x=\vec u\) and \(\vec a_x =0\) and \(\vec S_x =1.5cm\) so, \(t=\frac{1.5}{\sqrt{ \frac{4KeV}{m}}}\) now, for \(\vec S_y=\vec u_y t + \frac{1}{2} \vec a_y t^2\), but this time,\(\vec u_y=0\), \(\vec a_y = \vec a = \frac{q \vec E}{m}\) so, \(\vec S_y= \frac{1}{2} \vec a_y t^2\) sub it all in to get the displacement along the y axis. Do you need further help?
Cartesian coordinate system + newton law+Gauss's Law+Coulomb's Law=electric field