Tackling a Tough Physics Problem: Proton's Turning Point

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Homework Help Overview

The problem involves a proton being shot away from an infinite charged plane with a specified surface charge density. Participants are tasked with determining how far the proton travels before reaching its turning point, which requires understanding electric fields and forces acting on charged particles.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss finding the electric field due to the charged plane and applying the Lorentz force law to determine the force on the proton. There are questions about the lack of information regarding the electric field and the applicability of the Lorentz force law in this context.

Discussion Status

The discussion is ongoing, with some participants providing guidance on using the Lorentz force law and others expressing uncertainty about the electric field's value. There is a recognition of the need for further clarification on the electric field to proceed with the problem.

Contextual Notes

Participants note that the Lorentz force law has not been covered in their coursework, which may impact their ability to apply it effectively. There is also a mention of missing information regarding the electric field strength necessary for calculations.

spatel600
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The surface charge density on an infinite charged plane is - 2.30 *10^-6 A proton is shot straight away from the plane at 2.20*10^6m/s .



How far does the proton travel before reaching its turning point?

I've tried this problem a few times and got 3 different answers...any suggestions?



Thanks so much for your help.
 
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Find the E field due to the charged plane. Use the Lorentz force law to find the force on the proton due to this field. Use Newton's second law to find the acceleration due to the force. Use kinematics to find the zero of velocity.

- Warren
 
We haven't covered Lorentz force law.

Any more tips?

Thanks a bunch.
 
The Lorentz force law is:

[tex]\mathbf{F} = q \mathbf{E} + \mathbf{v} \times \mathbf{B}[/tex]

When the magnetic field is zero, it reduces to just

[tex]\mathbf{F} = q \mathbf{E}[/tex]

Given the electric field strength, all you need to do to find the force on a particle is multiply by the particle's charge.

- Warren
 
But what is the E field...its not given...


Any input?


Thanks.
 
Got it...thanks!
 

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