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#### jdpaul14

10+ Year Member
7+ Year Member
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.

#### Compass

##### Squishy
Moderator Emeritus
10+ Year Member

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

7+ Year Member
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

#### Seraph 84

SDN is not a place for homework questions, get in touch with your professor.

OP
J

10+ Year Member
7+ Year Member

#### Compass

##### Squishy
Moderator Emeritus
10+ Year Member
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.

#### capn jazz

10+ Year Member
7+ Year Member
These really aren't MCAT style questions.

#### plsletmein

##### im on bended knees
These really aren't MCAT style questions.
That's because they aren't. He wants people to do his homework for him and baited some people hook line and sinker into doing it

#### capn jazz

10+ Year Member
7+ Year Member
And he was rude on top of that.

#### bruceleehiiiyaa

##### Membership Revoked
Removed
10+ Year Member
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.

#### Compass

##### Squishy
Moderator Emeritus
10+ Year Member
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.

#### wanderer

10+ Year Member
5+ Year Member
These really aren't MCAT style questions.
Yea, especially the transformer question. When's the last time they asked about transformers?

#### ksmi117

##### GEAUX TIGERS!!!
Moderator Emeritus