Electron through electric and magnetic field

AI Thread Summary
To determine the initial accelerating voltage V for an electron to travel undeflected in electric and magnetic fields, the forces acting on the electron must balance. The upward force due to the electric field (F = eE) must equal the downward force from the magnetic field (F = evB). Given E = 1000 V/m and B = 1 × 10^(-5) T, the relationship can be expressed as eE = evB, leading to the condition that v = E/B. The voltage V can then be calculated using the kinetic energy equation, V = (0.5mv^2)/e, substituting the expression for v derived from the forces. This approach allows for the calculation of the required voltage to maintain the electron's trajectory without deflection.
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Homework Statement



An electron, initially at rest, is accelerated by a potential V in a vacuum and
then travels horizontally in a region of space where there is an electric field,
E, and a magnetic field, B. The fields are aligned such that the electron
is subjected to a force eE upwards and a force evB downwards, where e
is the charge of the electron and v is its velocity. If E = 1000 V/m and
B = 1 × 10^(-5) T, what is the value of the initial accelerating voltage V for
the electron to continue flying undeflected?
(Take m=10^(-30) kg and e=1.6×10^(-19) C)

Homework Equations



No idea.

The Attempt at a Solution



No idea.
 
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some equations for you:

upward F=qE
downward F=Bqv

(travelling straight so upward F=downward F)

Then, regarding voltage:

V=E/q=(0.5mv^2)/q

can you find the voltage from these equations?
 
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