I can't do this question. Please help me

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In summary, the conversation discusses the acceleration and deflection of electrons in a CRT. The question asks for an estimation of the value of the uniform electric field E, which causes the electrons to be deflected upward and reach the screen. The conversation suggests drawing a diagram to visualize the forces acting on the electron and to calculate the force and its relationship to intensity. The person also mentions the possibility of a magnetic field causing the deflection.
  • #1
DLK
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I can't do this question. Please help me:(

In a given CRT, electrons are accelerated horizontally by 6.0kV . They then pass through a uniform electric field E for a distance of 3.1cm , which deflects them upward so they reach the screen top 19cm away, 13cm above the center.

Estimate the value of E.
 
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  • #2


Have you tried drawing a diagram?

Make it systematic, draw all the forces that act on the electron. When the force is acting on an electron, it's velocity vector is changed. How? Can you calculate from the given information the force acting on the electron while passing through the electric field? How is that force related to intensity?

P.S. I thought that it was Magnetic field caused by coils with Lorentz force acting on the particles in a CRT.
 
  • #3


It is understandable that you may be struggling with this question. As a scientist, my recommendation would be to approach this problem by using the known values and equations related to electric fields and electron deflection. First, we can use the equation F = Eq to calculate the force exerted on the electrons by the electric field. We know that the force must be equal to the force of gravity, which is given by mg, where m is the mass of the electron and g is the acceleration due to gravity. By setting these two forces equal to each other, we can solve for E.

Additionally, we can use the equation v = √(2qV/m) to determine the velocity of the electrons after they have been accelerated by the 6.0kV potential. This velocity, combined with the distance the electrons travel in the electric field, can be used to calculate the time it takes for the electrons to reach the screen. This time can then be used in the equation d = 1/2at^2 to solve for the acceleration of the electrons in the vertical direction, which is also equal to Eq/m. By substituting this value for Eq/m into the previous equation, we can solve for E.

I hope this explanation helps guide you in solving this question. Remember to always use the known values and equations to approach scientific problems systematically. If you are still having trouble, don't hesitate to seek further assistance from a teacher or tutor.
 

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