# An electron is launched between two plates

• sliperyfrog
In summary, the conversation discusses the minimum speed an electron must have to pass between two parallel conducting plates separated by a distance d and with a uniform magnetic field of magnitude B. The conversation also addresses the electric field needed to prevent the electron from deflecting and determines the polarity of the plates required to provide this field. The attempt at a solution involves using equations F = BIL and F = ma, but the correct formula for the force of an electron in a magnetic field is F = evB. The trajectory of an electron in a magnetic field is circular.
sliperyfrog

## Homework Statement

An electron is launched between two parallel, neutral, conducting plates that are each L long and separated by a distance d with a uniform magnetic field of magnitude B permeated between them.

(a) What is the minimum speed the particle must have to traverse the region without striking either plate?

(b) What electric field prevents the electron from deflecting? Indicate the polarity of the plates (once charged) if they are to provide this field.

[/B]
F = BIL

F = ma

## The Attempt at a Solution

[/B]
So what i did was set the equations equal to each other to get BIL = ma then I turned a into dv/dt and turn I into q/t getting me BqL/t = mdv/dt I then rearrange the equation so look like BLq/mt dt = dv I then took the integral of both sides and got v = (BqL/m)ln(t) the problem is I don't how to get d into the equation and I don't think t should be in the answer.

Last edited:
Hi, mmm strange combination of formulas ... , the force of an electron ##e## that moves with a velocity ##v## in a magnetic field ##B## is ##F=evB##...

A second hint: think if the trajectory of an electron in a magnetic field will be linear or circular ?

## 1. What is the purpose of launching an electron between two plates?

The purpose of launching an electron between two plates is to study the behavior and properties of electric fields.

## 2. How is the electron launched between the two plates?

The electron can be launched using a device called an electron gun, which accelerates the electron and directs it towards the plates.

## 3. What happens to the electron once it is launched between the two plates?

The electron will experience a force due to the electric field between the plates and will either be attracted or repelled depending on the charge of the plates.

## 4. What factors affect the path of the electron between the two plates?

The factors that affect the path of the electron include the strength of the electric field, the distance between the plates, and the charge of the plates.

## 5. What can be learned from launching an electron between two plates?

By launching an electron between two plates, scientists can gather data on the behavior of electric fields and how they interact with charged particles. This can help in understanding various phenomena in physics and developing new technologies.

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