Determining Speed at Points A, B, and C

In summary, two parallel plates A and B, separated by 5.0cm, have an electric potential of 200V. An electron starting from rest at time t_A reaches plate B at time t_B and goes through an opening to reach point C at time t_C. The electron's velocity throughout the trip remains constant at 8.4*10^6m/s, as calculated using the equation v=sqrt[2qV]/m. The Work Energy Theorem is used to consider the initial and final velocities of the electron, which are both assumed to be zero. The 5.0cm separation between the plates helps in maintaining uniformity of the electric field lines.
  • #1
roy5995
29
0
Two parallel plates A and B are separated by 5.0cm. The electric potential between the plates is 200V. An electron starts from rest at time t_A and reaches plate B at time t_B. Then the electron goes through an opening and reches point C at time t_C.
What are the speeds at t_A , t_B and t_C?

+ -
| |
| |
A_B__C
| |
| |
+ -
 
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  • #2
If i use the equation

v=sqr root of [2qV]/m
q=1.602*10^-19
V=200V
m=9.1*10^-31

v=8.4*10^6

I can find velocity. but this means that the velocity will remain the same throughout the whole trip.

Will the electric potential or charge change during the whole trip?
Does the 5cm that the plates are separates affect anything?
 
  • #3
You are applying the Work Energy Theorem which considers final and initial velocity

Moreover why should e move from + plate to - plate starting from rest all the forces are against the motion
 
  • #4
Originally posted by himanshu121
You are applying the Work Energy Theorem which considers final and initial velocity

Moreover why should e move from + plate to - plate starting from rest all the forces are against the motion

Sorry, you're right, the diagram sould look like this

- +
| |
| |
A_B__C
| |
| |
- +
 
  • #5
What is the work energy theorem?

What equations can i use to find the initial and final velocities?
Or should i automatically asume that those velocities are zero?(b/c their potential energies are 0) and that the velocity in the middle (plate B) is 8.4*10^6m/s?

Once the electron passes through the positive plate, would it be attracted back to the plate?

How does the 5.0 cm that the plates are separated affect anything?
 
  • #6
Work Energy Theorem States that

[tex] \Delta K = W_{conservative forces}+W_{non conservative forces}[/tex]

[tex] \Delta K = K_f-K_i [/tex]
 
Last edited:
  • #7
With the small distance separating them signifies that the electric field lines are concentrated and are almost parallel to it. Which helps in maintaining uniformity.
 

1. How do you calculate the speed at points A, B, and C?

To determine the speed at points A, B, and C, you need to measure the change in distance over a given time interval. This can be done using a stopwatch or other timing device, and by recording the starting and ending positions of the object. Then, divide the change in distance by the time interval to calculate the speed in units of distance per time (e.g. meters per second).

2. What is the difference between instantaneous speed and average speed?

Instantaneous speed refers to the speed of an object at a specific moment in time, while average speed is the overall speed of an object over a given time interval. Instantaneous speed can be calculated by finding the slope of the tangent line to the position-time graph at a specific point, while average speed is calculated by dividing the total distance traveled by the total time taken.

3. How does the speed at point B affect the overall motion of an object?

The speed at point B, along with the speeds at points A and C, can give us information about the acceleration of an object. If the speed at point B is constant, then the object is moving at a constant velocity and has zero acceleration. If the speed at point B is increasing, then the object is accelerating in the positive direction. If the speed at point B is decreasing, then the object is decelerating or accelerating in the negative direction.

4. Can we determine the direction of motion from the speed at points A, B, and C?

No, the speed at points A, B, and C only tells us information about the magnitude of the velocity, not the direction. To determine the direction of motion, we would need to analyze the position-time graph or use other methods such as vector addition.

5. How can we use the speed at points A, B, and C to calculate the distance traveled by an object?

To calculate the distance traveled by an object, we can use the formula distance = speed * time. We can use the speed at points A, B, and C to calculate the average speed over a given time interval, and then multiply it by the total time taken to find the total distance traveled. Alternatively, we can use the trapezoidal rule to estimate the area under the velocity-time curve to get a more accurate measure of the distance traveled.

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