AP phys C e&m review

god damn this EXAM

A charge of magnitude 2 nC is placed at the origin. An identical charge is placed 2 millimeters from the origin on the x axis, and a third identical charge is placed 2 millimeters from the origin on the y axis. What is the magnitude of the force on the charge at the origin?

  

0\.0127 N

Two charged balls are separated by a certain distance. If the magnitudes of their charges are doubled, and the distance between them is halved, the electrical force between the balls will ___________.

  

increase by a factor of 16

A faraday is defined as charge equal to NA protons.

(Avogadro's Number NA = 6.02 x 1023)

Find the number of coulombs in 1 faraday.

(use qp = 1.6 x 10-19 C)

96,320

If the distance between two charges is doubled, the force is____________.

  

decreased by a factor of 4

What is the electric force exerted on a charge of -1.2 μC at a point where the electric field is 2500 N/C?

  

\- 0.0030 N

What is the magnitude and direction of the electric field generated by a 13 μC charge in a point 8.90 cm away from the charge?

1\.48 x 107 N/C, directed away from the charge

A +2 μC charge is at the origin. A +5 μC charge is on the x-axis at +1 m. At what point between the charges is the electric field zero?

\+38.7 cm

How much work is required to bring a 10 μC  charge from infinity to 5.00 meters away from a point charge of -2 μC?

\-3.60x10^-2 J

Two identical charges q are placed on the x axis, one at the origin and  the other at x = 5.0 cm.

A third charge -q is placed on the x axis so  the potential energy of the three-charge system is the same as the potential energy at infinite separation.

What is the coordinate of the third charge?

13 cm

A 3.0μC point charge is at the origin of a coordinate system. Another point charge of -6.0μC is at x = 1.0 m. What is the electric potential at the point where x = 0.50 m?

\-5.4x10^4 V

What is the charge on a 0.25 μF capacitor when the capacitor is connected to a 9.0 V battery?

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2\.3x10^-6 C

A parallel plate capacitor has plate separation of 4.0 cm and a plate area of 4.0x10-2 m2. What is the capacitance of this capacitor?

8\.9x10^-12 F

The electric field just outside of a conductor that is in electrostatic equilibrium _____________.

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is perpendicular to the conductor’s surface

A 100 meter long copper wire has a resistance of 100 Ω. Another copper wire has the same mass but is 10 meters long. Find the resistance of the second wire.

  1 Ω

Electrical resistance in a wire depends on the wire’s _____________.

I. conductivity

II. length

III. thickness

All of the above

A 5.5 m long aluminum wire has a resistance of 0.40 Ω, ρ = 2.82x10-8 Ωm and α= 4.29x10-3 oC-1. Its conductivity is:

  3.6x10^7 (1/Ωm)

If more resistors are added in series to a battery with zero internal resistance, the power supplied by the source ___________.

decreases

Two 15 Ω and three 25 Ω light bulbs are connected in series and hooked up to a 24 volt battery. Find the current through each bulb.

0\.229 A

Three capacitors of values of 1.0 μF, 1.5 μF, and 2.0 μF each are connected in series. What is the equivalent capacitance?

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  0.46 μF

Find the currents through the 8 Ω resistor at the instant that the switch is closed.

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0\.545 A

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What force acts between two charges of 3 μC and 8 μC if they are separated by a distance of 103 mm?

20\.3 N

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Four charges q1, q2, q3 and q4, are placed at the corners of a square. Charges q1 and q4 are located on opposite corners and have equal charges. Both q2 and q3 have a charge of 1.0 C. If the force on q2 is zero, what is the charge on q1?

\-0.35 C

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Two charges, q1 and q2, are separated by a certain distance. The ratio of charge q1 to charge q2 is 1:2. What is the ratio of the magnitude of the force on q1 to the magnitude of the force on q2?

1:1

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An electric field exerts force of 2.60 N on a 3.40 x 10-8 C charge. What is the magnitude of the electric field?

7\.65 x 10^7 N/C

Find the magnitude of the electric field if the string with a 7 gram ball carrying a charge of 4 x 10-9 C forms an angle of 35o with the vertical.

1\.20 x 10^7 N/C

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The electric field of an isolated, uniformly charged metallic sphere is greatest ____________.

at the sphere’s outer surface

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A parallel plate capacitor is connected to a battery that maintains a constant potential difference. How will the electrical energy stored on the capacitor change if the separation between the plates is doubled?

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It will be cut in half.

The heating coil of a water heater has a resistance of 20 ohms and operates at 210 V. How long does it take to raise the temperature of 200 kg of water from 15oC to 80oC?

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6\.86 hr

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A 500 watt heater carries a current of 4 A. What is the resistance of the heating element?

31\.3 Ω

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A 6 Ω and a 12 Ω resistor are connected in parallel. This combination in turn is connected in series with a 4 Ω resistor. What is the equivalent resistance of this combination?

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8 Ω

What will be the electric potential at a distance of 0.15 m from a point charge of 6 μC?

3\.6x10^5 V

Two point charges of +2.00 μC and -2.00 μC are 0.100 m apart. What is the electric field at the point midway between the two charges?

1\.44 x 10^7 N/C

at what distance is the box in equilibrium

4\.51 m

A charge of magnitude 2 nC is placed at the origin. An identical charge is placed 2 millimeters from the origin on the x axis, and a third identical charge is placed 2 millimeters from the origin on the y axis. What is the magnitude of the force on the charge at the origin?

0\.0127 N

Charge q1 = +2.00 μC is at -0.500 m along the x axis. Charge q2 = -2.00 μC is at 0.500 m along the x axis. Charge q3 = 2.00 μC is at 0.500 m along the y axis. What is the magnitude of electrical force on charge q3 due to the others?

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1\.02 X 10^-1 N

A 43 gram mass carrying a charge of 9 μC is suspended in a vertical upward-directed electric field. What is the magnitude of the electric field?

4\.69 x 10^4 N/C

Electric potential is defined as the _________________________.

  

potential energy per unit charge

Which of the following Gaussian surfaces would be the simplest to use to determine the electric field intensity near a long, straight, charged wire?

 

A cylinder whose axis coincides with the wire.

Two identical charges q are placed on the x axis, one at the origin and  the other at x = 5.0 cm.

A third charge -q is placed on the x axis so  the potential energy of the three-charge system is the same as the potential energy at infinite separation.

What is the coordinate of the third charge?

13 cm

The electric field of an isolated, uniformly charged metallic sphere is greatest ____________.

at the sphere’s outer surface

Two parallel metal plates are 5 cm apart and have equal surface charge densities of 9 nC/m2 of opposite signs on their inner surfaces. What is the electric field between the plates?

1020 N/C

A copper cable carries a current of 300 A. If the power loss is 2 W per meter, find the radius of the cable. (The resistivity of copper is 1.7x10-8 Ωm.) 

1\.6 cm

From the given diagram, determine the charge stored on the 40 uF capacitor

0\.0114 C

If more resistors are added in series to a battery with zero internal resistance, the power supplied by the source ___________.

decreases

Two capacitors of 4 μF and 8 μF are connected in parallel. What is the equivalent capacitance of this system?

12 μF

A mass with a charge of 4.60 x 10-7 C rests on a frictionless surface. A compressed spring exerts a force on the mass on the left  side. Three centimeters to the right of the mass is a 7.50 x 10-7 C fixed charge. How much is the spring compressed if its  spring constant is 14 N/m?

24\.6 cm

How many electrons make up a charge of -3.2 x 10-19 C?

2

What is the change in potential energy of a proton as it moves from x = 5 m to x = 2 m in a uniform electric field that is parallel to the positive x-axis and directed toward the origin, if the magnitude of the electric field is 5.0x102 N/C?

\-2.4x10^-16 J

A hollow metal sphere is charged to a potential of 40 V. The potential at its center is ________.

40 V

A 6.00 µF parallel plate capacitor has a charge of +40 μC. What is the potential energy stored in this capacitor?

  

133 μJ

A constant 10 A current flows in a circuit with a resistance of 200 Ω. The net charge passing through any point in the circuit during a 1 minute interval is _______.

600 C

What will be the final charge on the capacitor after the switch is closed and equilibrium has been reached?

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99\.6 µC

A 2 Ω resistor is connected to a battery with an emf of 6.30 V. What is the total power dissipated by the resistor?

19\.8 W

Two capacitors having values of 10 μF each are connected in parallel and then hooked up to a 9.0 V battery. How much energy must the battery supply to charge the capacitors?

8\.1x10-4 J

A +2 μC charge is at the origin. A +5 μC charge is on the x-axis at +1 m. At what point between the charges is the electric field zero?

\+38.7 cm

An electron moves 0.10 m along the direction of an electric field of a magnitude of 3.0 N/C. What is the change in electric potential energy between the electron’s initial and final points?

4\.8x10^-20 J

A charge +Q is uniformly distributed throughout a nonconducting spherical shell of inner radius R1 and outer radius R2, as shown above. The electric field is determined at a distance r from the center of the spherical shell. The electric field for r < R1 is:

zero

The capacitance of a parallel plate capacitor is _________.

  

proportional to the area of the plates

A 0.20 m long metal wire has a radius of 1 cm and a resistance of 3.2x10-5 Ω. What is the resistivity of the metal?

5\.0x10^-8 Ωm

How would Coulomb's Law be written if the charge of an electron was instead defined as positive and the proton as negative?

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F = kQq/r^2

Four negative charges of a magnitude of -6 nC each form a square, 12 cm on a side. Find the magnitude of electric field at the center of the square.

0 N/C