Electric Fields Question, What is the speed of the electron?

In summary: So the total work done is F*d=1/2mv^2 whereF=qE+qV*B+mgm is the mass of the electron, E is the electric field, V is the velocity of the particle, B is the magnetic field (in the z direction), q is the charge of the particle, and g is the gravitational acceleration.In summary, to find the speed of an electron released from rest in a weak electric field, you need to use the equation F=qE+qV*B+mg and solve for v. The electric field, magnetic field, and gravitational acceleration are given in the problem, and the mass and charge of the electron can be looked up.
  • #1
Rangers1994
2
1

Homework Statement


An electron is released from rest in a weak electric field given by -2.8 x 10^-10 N/C [PLAIN]https://www.flipitphysics.com/Content/smartPhysics/Media/Images/Tipler/Symbols/jhatbold.gif. After the electron has traveled a vertical distance of 1.9 µm, what is its speed? (Do not neglect the gravitational force on the electron.) Answer should be in mm/s.

Any help towards setting up this problem or what formula to use will be greatly appreciated.

Homework Equations


E=F/q
F=qE+qV*B

F= (1/4πE0)(q1q2/r^2)
Fnet=Fg=ma=mg

Work Done = F*d = 1/2(mv^2)

The Attempt at a Solution


I don't really know where to start, this is the last problem on my assignment and I only have a few attempts left, we did not go over this in class yet and our class uses "Flipit Physics" videos instead of a book.

I tried Fe=qE
=(1.602x10^-19)(-2.8x10^-10) = -4.4856x10^-29
then a = Fe/m
= -4..572477064 x 10^-31 which was wrong

I also tried Work Done = F*d = 1/2(mv^2) and solved for v but that was also wrong.
 
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  • #2
E=1/2mv^2 is equal to the total work done on the particle. You have two forces: the Lorentz force F=q(E+v*B) and gravitational force F=mg, both in the same direction (I assume j-hat is the unit vector in the y direction).
 

1. What is an electric field?

An electric field is a physical field that surrounds an electrically charged particle or object. It describes the influence that the charged particle has on other charged particles in its vicinity.

2. How is an electric field created?

An electric field is created by a charged particle or object. This can be through the presence of an excess or deficit of electrons, or through the separation of positive and negative charges.

3. What is the direction of an electric field?

The direction of an electric field is defined as the direction that a positive test charge would move if placed in the field. It is always directed away from positive charges and towards negative charges.

4. How does the speed of an electron relate to the electric field?

The speed of an electron is affected by the strength of the electric field it is in. The stronger the electric field, the greater the force on the electron and the greater its speed will be.

5. What factors can affect the speed of an electron in an electric field?

The speed of an electron in an electric field can be affected by the strength of the field, the mass of the electron, and any other forces acting on the electron (such as magnetic forces).

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