Magnetism Questions

[HopefulOncoDoc]

If an electron can move between two parallel conducting plates producing and electric field, then the acceleration that the electron experiences due to the electric field:

A. does not depend on its position between the plates.
B. is always opposite to the acceleration due to gravity.
C. is zero because the electric field is perpendicular to the velocity of the charged particle.
D. is a right angles to the electric field.

The answer is A.

Could someone please explain this to me? Thanks!

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[WorldChanger36]

If an electron can move between two parallel conducting plates producing and electric field, then the acceleration that the electron experiences due to the electric field:

A. does not depend on its position between the plates.
B. is always opposite to the acceleration due to gravity.
C. is zero because the electric field is perpendicular to the velocity of the charged particle.
D. is a right angles to the electric field.

The answer is A.

Could someone please explain this to me? Thanks!

This one is a process of elimination question. As you go down your answer choices A doesn't jump out at you as a "good" answer so you move on to B. With B you may think that if your electric field is strong it can overcome gravity so the term always tells you that B can't be right. Move on to C and you may or may not know the direction of the electron to determine if C is correct but if you look at D you will note that it is stating the same thing as C. Right angle mean perpendicular and because you can not have two right answer C and D are out and B was already ruled out so that leaves A. If you really think about it does the position of the electron matter when producing a field? Only if you need to know Voltage which you don't. Process of elimination.

 

[Econ2MD]

The electric field in a parallel plate capacitor is constant. You can memorize that and be done with it if you want. If you think about it, though, the electron is pushed by one end and pulled by the other. The strength of the force is inversely proportional to the square of the distance between electron and plate ( similar to Q1Q2/R^2 for point charges). As you get closer to one plate, you get farther from the other, and the net effect is a constant field and force on the electron.

 

[Vanguard23]

From what I gathered from a TBR passage: It doesn't matter because the force is constant at all points between the plates. Why? Because it's coming from a negatively charged plate, to a positively charged plate. The further from the negatively charged side, the less "pushing" force. However, the closer to the positively charged side the more "pulling" force. Throw in the equation by Econ, and you can understand it quantitatively.