PHYS 251 Chapter Notes - Chapter 21.1-21.3: Electric Potential Energy, Electric Potential, Voltage

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2 Nov 2016

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The ele(cid:272)tri(cid:272) pote(cid:374)tial e(cid:374)ergy of a (cid:272)harge (cid:272)a(cid:374) (cid:271)e deter(cid:373)i(cid:374)ed (cid:449)he(cid:374) it"s at a parti(cid:272)ular positio(cid:374) (cid:271)y computing how much work it took to move the charge to that position. Electric potential: the potential for creating potential energy (cid:1847)elec=(cid:1848) The electric potential is created by the source charges and is present at all points in space. Electric potential tells us how the source charges would provide q with potential energy. The unit of electric potential is the joule per coulomb, also called the volt (v) When there is no force on charge q, no work needs to be done to move it from a to b so electric. 21. 2 sources of electric potential potential energy remains unchanged so that (cid:4666)(cid:1847)elec(cid:4667)a=(cid:4666)(cid:1847)elec(cid:4667)b. Potential difference = (cid:1848)=vb va and is zero. A potential difference is created by separating a positive and negative charge. Battery: creates a fixed potential difference, use chemical reactions to create an internal charge separation.

Related Questions

A charge q that moves between two points A and B, and has anelectric force acting on it ( and perhaps several other forces) haswork W done on it by the electric force. The electrostatic force isconservative and so we can define a change in electric potentialenergy, Delta U = -W. We defined electric field using the relationF^^\-> = q E^^\->, and in a similar way we define electricpotential commonly called voltage as
Delta V = V_B - V_A = -W/q=(Delta U)/q or equivalently q Delta V =q (V_B - V_A) = -W=Delta U

A ball has mass 3.0 Âµg and charge -6 nC moves from point A to pointB. It has the same speed at points A and B, and the work done bythe electric field during the move is -1.5 mJ.
(a) What is the change in electric potential energy of the ball?1
(b) What is the change in voltage between points A and B? 2
(c) At which point does the ball have a higher electric potentialenergy?
(d) Which point has the higher voltage?
(e) Has the kinetic energy of the ball changed?

a)The figure below shows a test charge q betweenthetwo positive charges. Find the force (in newtons) on thetestcharge for q = 2 ÂµC. Give a positive answer iftheforce is to the right and a negative answer if the force is totheleft.

b) For the previous question, find the electric field(innewtons/coulomb) at the position of test charge. Again, supplyapositive value if the electric field points to the right andanegative value if it points to the left.

c) How much work (in joules) is done in moving a charge of 2.5Î¼Cadistance of 53 cm along an equipotential at 10~V?

d) The field lines associated with a uniform electric fieldina region of space are shown in the figure below. Imaginedrawingtwo equipotentials in the plane of the figure, one passingthroughpoint A and and one passing through point B. If the electricfieldis 450 N/C, how much does the potential change in going from AtoB? Provide your answer in volts and use a positive value ifitincreases and a negative value if it decreases.

Please help and you will get a lifesaver rating!! Thankssomuch

Two charges, +4ÂµC on the left and -9ÂµC on the right, are separatedby 30cm.

1. What is the magnitude and direction of the electric force actingon the -9ÂµC charge?

2. What is the magnitude and direction of the electric fieldmeasured at a point 10cm to the right of the +4ÂµC charge?

3. At what point in space will the electric field due to thesecharges be zero?

4. What is the sign and magnitude of the electric potential at apoint 10cm to the right of the +4ÂµC charge?

5. How much work would it require to separate these two charges toan infinite distance?

6. A disposable camera has a 1.5-V battery with an internalresistance of 5000?. To prepare for usage of the flash, the batterycharges a capacitor of 30mF.

a.) How long will it take the capacitor to charge up to 1.35V, 90%of the batteryâs EMF?

b.) How much energy is stored in the capacitor when it holds thefull 1.5V of the battery?

7. The shutter switch disconnects the capacitor from the battery,and places it across a flashbulb with resistance of 100?.

a.) How long will it take for the capacitor to release 50% of itsstored energy through the flashbulb?

b.) What was the average power burned by the resistor over thattime?

PHYS 251 Chapter Notes - Chapter 21.1-21.3: Electric Potential Energy, Electric Potential, Voltage

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