8 hard Physics Problems I am having trouble with...please help!!!!

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jdpaul14

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1) A proton is released from rest in a region of space with a nonzero electric field. As the proton moves, does the electric potential energy of the system increase, decrease, or stay the same? Explain.

2) How far must the point charges q1 = +7.22 uC and q2 = -26.1 uC be separated for the electric potential energy of the system to be -126J?

3) To operate a given flash lamp requires a charge of 32 uC. What capacitance is needed to store this much charge in a capacitor with a potential difference between its plates of 9.0V?

4) The separation of b/w the plates of of a parallel plate capacitor is doubled and the area of the plates is halved. How is the capacitance affected?

5) A 75W lightbulb operates on a potential difference of 95V. Find (a) the current in the bulb and (b) the resistance of the bulb. (c) If this bulb is replaced with one whose resistance is half the value found in part (b), is its power rating greater than or less than 75W? By what factor?

6) A wire with a current of 2.8 A is at an angle of 36 degrees relative to a magnetic field of 0.88T. Find the force exerted on a 2.25 m length of wire.

7) Explain what happens when the angular speed of the coil in an electric generator is increased.

8) Transformer 1 has a primary current Ip and a secondary current Is. Transformer 2 has twice as many turns on its primary coil as transformer 1, and both transformers have the same number of turns on the secondary coil. If the primary current on transformer 2 is 3Ip, what is its secondary current? Explain.
 

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I've provided you with formulas for the first few. Telling you the answer won't help you.

1) A proton is released from rest in a region of space with a nonzero electric field. As the proton moves, does the electric potential energy of the system increase, decrease, or stay the same? Explain.
Look at the three options:

Decrease - Potential Energy being converted to movement.

2) How far must the point charges q1 = +7.22 uC and q2 = -26.1 uC be separated for the electric potential energy of the system to be -126J?
kqq/r^2

Solve

3) To operate a given flash lamp requires a charge of 32 uC. What capacitance is needed to store this much charge in a capacitor with a potential difference between its plates of 9.0V?
C=Q/V

4) The separation of b/w the plates of of a parallel plate capacitor is doubled and the area of the plates is halved. How is the capacitance affected?
C=er*e0*A/d

5) A 75W lightbulb operates on a potential difference of 95V. Find (a) the current in the bulb and (b) the resistance of the bulb. (c) If this bulb is replaced with one whose resistance is half the value found in part (b), is its power rating greater than or less than 75W? By what factor?
P=I^2R=IV

6) A wire with a current of 2.8 A is at an angle of 36 degrees relative to a magnetic field of 0.88T. Find the force exerted on a 2.25 m length of wire.

7) Explain what happens when the angular speed of the coil in an electric generator is increased.

8) Transformer 1 has a primary current Ip and a secondary current Is. Transformer 2 has twice as many turns on its primary coil as transformer 1, and both transformers have the same number of turns on the secondary coil. If the primary current on transformer 2 is 3Ip, what is its secondary current? Explain.
 

Doodl3s

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For question two the correct equation is U=kqq/r... r^2 is for force...

for 6.) ILBsin(theta)
for 7, you need a passage to explain that more.. and 8, i know its directly or indirectly proportional to the number of turns... i forget... cause i know doubling the wire length with double the resistance and half the current. But if you're talking about a coil in a magnetic field, theres twice as much coil in the field so its actually double.... I need to know about the generator here lol
 
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SDN is not a place for homework questions, get in touch with your professor.
 
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jdpaul14

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Thanks guys!...Seraph, did anyone ask for your opinion? Learn some manners.
 

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Squishy
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For question two the correct equation is U=kqq/r... r^2 is for force...

for 6.) ILBsin(theta)
for 7, you need a passage to explain that more.. and 8, i know its directly or indirectly proportional to the number of turns... i forget... cause i know doubling the wire length with double the resistance and half the current. But if you're talking about a coil in a magnetic field, theres twice as much coil in the field so its actually double.... I need to know about the generator here lol
Thanks for fixing that. I tried to look up the equation, but thinking about the MCATs at the moment is RARGH and I'm done with them.
 

bruceleehiiiyaa

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i have to disagree with number 1.

i think the electric potential does not change/stays the same.

EPE is just voltage guys. and the question refers to the SYSTEM. V=Ed. it has nothing to do with the proton.
 

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Squishy
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i have to disagree with number 1.

i think the electric potential does not change/stays the same.

EPE is just voltage guys. and the question refers to the SYSTEM. V=Ed. it has nothing to do with the proton.
OH, SYSTEM. Oops.
 
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