Electric Potential Difference homework help

In summary, a small test charge is launched from point X and is observed to pass through point Y. The speed of the test charge at point Y is greater than, less than, or equal to the speed of the test charge at point X.
  • #1
cy19861126
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Homework Statement


Two charged rods, each with net charge -Qo, are held in place as shown in the diagram below
a) A small test charge -qo travels from point X toi point Y along the circular arc shown.
i. Draw an arrow at each point (X and Y) to show the direction of the electric force on the test charge at that point.
ii. Is the work done on the charge by the electric field positive, negative, or zero?
iii. Is the electric potential difference positive negative or zero?

b) The test charge is launched from point X with initial speed vo and is observed to pass through point Y. Is the speed of the test charge at point Y greater than, less than or equal to vo?


Homework Equations


V = (delta PE)/q
W = Fd


The Attempt at a Solution


a) i. The electric force at X is pointing at southwest direction and force at Y is pointing at North direction
ii. Positive. W = Fd. For the rod on the left, the force exerted on the object is 0, so the rod has no effect on the test charge. However, the rod on the right exerts a positive force on the test charge. This is because the force direction from the rod and the displacement are pointing at the same direction
iii. Negative. The difference in electric energy is positive because point X is closer to the negative rods than point Y. And since V = (delta PE)/q. Delta PE is positive and q is negative, so the electric potential difference must come out to be negative.

b) Greater than. -PE = KE. If electric potential energy is negative, then KE must be positive. Thus, greater velocity
 

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  • #2
Hi.Is this a show-case?
 
  • #3
Show case? What are you talking about. I put on the questions I have problems on and then I put the answers I thought to be correct. Although I don't expect any of them to be correct.
 
  • #4
I edited my question to make it look like a problem instead of a show case
 
  • #5
"However, the rod on the right exerts a positive force on the test charge. This is because the force direction from the rod and the displacement are pointing at the same direction"

I think it's negative force, as the charge is negative and negative charge repel negative.

"b) Greater than. -PE = KE. If electric potential energy is negative, then KE must be positive. Thus, greater velocity"

I think is same,the time spent on decelerating the charge is equal to the time spent on accelerating the charge,so end velocity=same.

Others I think assuming those info u gave're correct and based on my limited AS-lv knowledge and stuff are correct.
 
  • #6
inv said:
I think it's negative force, as the charge is negative and negative charge repel negative.
It doesn't matter if you define force to be positive or negative. You can set the coordinate system whichever way you want. But if the direction of force and the displacement traveled are the same, then work is positive. In this case, force and distanced traveled are the same, I think. If I am wrong, can anyone correct it for me?
 
  • #7
inv said:
I think is same,the time spent on decelerating the charge is equal to the time spent on accelerating the charge,so end velocity=same.
I thought that as long as there is constant force, there is always constant acceleration, unless force is changing at some point...
 
  • #8
C'mon, can someone answer my question please. I want to understand the problem rather than getting an answer. Any help will be appreciated.
 

What is electric potential difference?

Electric potential difference is the difference in electric potential energy between two points in an electric field. It is measured in volts (V) and represents the amount of work needed to move a unit of electric charge from one point to another.

How is electric potential difference calculated?

Electric potential difference is calculated by dividing the change in electric potential energy by the amount of charge that moves between the two points. This can be represented by the equation V = ΔU/q, where V is the potential difference, ΔU is the change in potential energy, and q is the amount of charge.

What is the unit of measurement for electric potential difference?

The unit of measurement for electric potential difference is volts (V). However, in some cases, it can also be measured in other units such as joules per coulomb (J/C) or electron volts (eV).

How does electric potential difference relate to electric current?

Electric potential difference is the driving force behind electric current. A higher potential difference means there is a greater force pushing the electric charges to move from one point to another, resulting in a larger electric current.

What factors affect electric potential difference?

Electric potential difference is affected by the distance between the two points, the amount of charge, and the electric field strength. It is also influenced by the material properties of the conductor and any resistances present in the circuit.

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