Speed of Impact of electrons in a television.

AI Thread Summary
The discussion focuses on calculating the speed of electrons impacting a television screen, specifically using a potential difference of 15,500 V. The relevant equations include kinetic energy and the relationship between energy, mass, and velocity. Initial attempts at solving the problem were incorrect, but the correct approach involves using the energy of the electrons, given as 2.48E-15 J, to find the speed. The solution ultimately relies on the kinetic energy formula, confirming the relationship between energy and velocity. The participant successfully resolved the calculation after clarifying their approach.
Yavko2510
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Homework Statement



What is the speed of impact of electrons with the screen of the picture tube? Answer in units of m/s.

Electrons are accelerated through a potential difference of 15500 V
Charge of electron: 1.6 x 10^-19 C
Mass of electron: 9.11 x 10^-31 kg
Energy of electrons when they hit the screen: 2.48E-15 J

Homework Equations



v=Ed
f=ma
f=qE
K = .5mv^2

The Attempt at a Solution



I tried using that equation, I made it 15500 = .5mv^2 ... obviously plugging in the above numbers for m and v.

Computer said the answer was wrong.
 
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Goodness they calculated the electron energy for you! Too easy!

So just use 2.48E-15 J = 1/2mv^2

Potential is the energy per charge, so you could start with V = E/q, and replace E with 1/2mv^2.
 
No, I calculated that for a previous problem...

Thanks though, got it right now.
 

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