Question 1

Find the magnitude and direction of the electrostatic force on the electron in the figure shown.

Accepted Answer

A) 5.07 *10-26 N to the left 
B) 5.07 * 10-26 N to the right 
C) 0 N 
D) 6.23 * 10-26 N to the left 
E) 6.23 * 10-26 N to the right 
A) 5.07 *10-26 N to the left 
B) 5.07 * 10-26 N to the right 
C) 0 N 
D) 6.23 * 10-26 N to the left 
E) 6.23 * 10-26 N to the right A

Question 2

A glass rod is charged by triboelectric charging and 13 * 1010 electrons removed.What is the charge on the rod?

Accepted Answer

A) + 6.40 nC 
B) -6.40 nC 
C) +20.8 nC 
D) -20.8 nC 
E) +8.12 nC 
A) + 6.40 nC 
B) -6.40 nC 
C) +20.8 nC 
D) -20.8 nC 
E) +8.12 nC C

Question 3

Two small,charged objects,Q1 and Q2,are some distance d apart from each other and there is a force F between them.What is the value of the force if Q1 is increased by a factor of two,Q2 is increased by a factor of 3,and d is increased by a factor of 5?

Accepted Answer

A) 0.20 F 
B) 0.24 F 
C) 0.12 F 
D) 1.2 F 
A) 0.20 F 
B) 0.24 F 
C) 0.12 F 
D) 1.2 F B

Question 4

A plastic ball of charge -5 nC is held 2 cm above a glass bead of charge +5 nC at rest on a table.For the glass bead to leap up to the plastic ball its mass must be

Accepted Answer

A) 57 $\mu$g. 
B) 65  $\mu$g. 
C) 81  $\mu$g. 
D) 98 $\mu$g. 
E) 112  $\mu$g. 
A) 57 $\mu$g. 
B) 65  $\mu$g. 
C) 81  $\mu$g. 
D) 98 $\mu$g. 
E) 112  $\mu$g.

Question 5

A small ball with a mass of 40 g and a charge of -0.3  $\mu$C is suspended from the ceiling on a string.The ball is suspended above an insulating floor.If a second small ball with a mass of 50 g and a charge of 0.6  $\mu$C is placed on the floor directly beneath the first ball and the tension in the string is 1.0 N,what is the distance between the first ball and the insulating floor?

Accepted Answer

A) 8.3 cm 
B) 7.0 cm 
C) 5.2 cm 
D) 5.7 cm 
E) 6.4 cm 
A) 8.3 cm 
B) 7.0 cm 
C) 5.2 cm 
D) 5.7 cm 
E) 6.4 cm

Question 6

In the opposite corners of a square there are two identical ions.Each has a charge of -e.The length of one side of he square is L.In one of the other corners there is a third ion which has a charge of +e.What is the magnitude of the net electrostatic force on the positive ion caused by the two negative ions?

Accepted Answer

A) ke2/2L2 
B) ke2/L2 
C)    ke2/L2 
D) 2ke2/L2 
A) ke2/2L2 
B) ke2/L2 
C)    ke2/L2 
D) 2ke2/L2

Question 7

Two point charges are fixed in space along the x-axis.The first charge of 3.8 $\mu$C is located at x = - 4.5 cm,while the second charge of -5.6 $\mu$C is located at x = 3.5 cm.Where should a third charge (with charge 1 $\mu$C)be placed on the x-axis so that the total electric force it vanishes?

Accepted Answer

A) -0.214 m 
B) 0.214 m 
C) -0.312 m 
D) -0.419 m 
E) 0.419 m 
A) -0.214 m 
B) 0.214 m 
C) -0.312 m 
D) -0.419 m 
E) 0.419 m

Question 8

Find the magnitude of the net force on a 1.20 mC charge at the origin if there is a +2.40 mC charge at (3.0m,0)and a -5.70 mC charge at (0,4.0m).

Accepted Answer

A) 1.8 kN 
B) 2.9 kN 
C) 3.8 kN 
D) 4.8 kN 
E) 16 kN 
A) 1.8 kN 
B) 2.9 kN 
C) 3.8 kN 
D) 4.8 kN 
E) 16 kN

Question 9

Three electrons are located at the vertices of an equilateral triangle,one at each vertex.The length of one side of the triangle is 1.00 nm.What is the magnitude of the net electrostatic force on each electron?

Accepted Answer

A) 2.30 * 10-10 N 
B) 3.25 * 10-10 N 
C) 3.99 * 10-10 N 
D) 4.60 * 10-10 N 
A) 2.30 * 10-10 N 
B) 3.25 * 10-10 N 
C) 3.99 * 10-10 N 
D) 4.60 * 10-10 N

Question 10

Which of the following have a smallest net force?

Accepted Answer

A) A 1-C charge a distance of 1 m from a -2-C charge. 
B) A 1-C charge a distance of 0.5 m from a -1-C charge. 
C) A 1-C charge exactly halfway between a -1-C charge and a 1-C charge separated by 2 m. 
D) A 1-C charge exactly halfway between two -2-C charges separated by 2 m. 
E) A 1-C charge a distance of 2m from a -4-C charge. 
A) A 1-C charge a distance of 1 m from a -2-C charge. 
B) A 1-C charge a distance of 0.5 m from a -1-C charge. 
C) A 1-C charge exactly halfway between a -1-C charge and a 1-C charge separated by 2 m. 
D) A 1-C charge exactly halfway between two -2-C charges separated by 2 m. 
E) A 1-C charge a distance of 2m from a -4-C charge.

Question 11

Two charged particles attract each other with a force

Accepted Answer

A) is 16 times stronger. 
B) is 4 time stronger. 
C) is twice as strong. 
D) remains the same. 
E) is 1/2 as strong. 
A) is 16 times stronger. 
B) is 4 time stronger. 
C) is twice as strong. 
D) remains the same. 
E) is 1/2 as strong.

Question 12

A 3.0 µC charge lies 10.0 cm to the right of a 2.0 µC on the x-axis.What is the magnitude of the force on the 2.0 µC charge?

Accepted Answer

A) 2.4 N 
B) 4.8 N 
C) 5.4 N 
D) 6.7 N 
E) 7.9 N 
A) 2.4 N 
B) 4.8 N 
C) 5.4 N 
D) 6.7 N 
E) 7.9 N

Question 13

0.482% of the electrons are removed from a sphere of iron (Z=26,A=56),resulting in a net charge of 1.00 C on the sphere.What is the mass of the iron sphere?

Accepted Answer

A) 4.64 mg 
B) 10.0 mg 
C) 3.19 mg 
D) 3.99 mg 
E) 6.20 mg 
A) 4.64 mg 
B) 10.0 mg 
C) 3.19 mg 
D) 3.99 mg 
E) 6.20 mg

Question 14

A particle (charge = -15.0 µC)is located on the x- axis at the point x = -25.0 cm,and a second particle (charge = +45.0 µC)is placed on the x- axis at x = +30.0 cm.What is the magnitude of the total electrostatic force on a third particle (charge = -3.50 µC)placed at the origin (x = 0)?

Accepted Answer

A) 2.33 mN 
B) 23.3 N 
C) 0.818 N 
D) 8.18 N 
E) 2.67 N 
A) 2.33 mN 
B) 23.3 N 
C) 0.818 N 
D) 8.18 N 
E) 2.67 N

Question 15

Two charges are placed at the corners of an equilateral triangle that is 0.25 m on each side.The first charge is 4.5 $\mu$C and the second is 3.2 $\mu$C.If a charge if 2.5 $\mu$C is placed at the third corner of the triangle,what is the magnitude of the electric force on the third charge due to the first two charges?

Accepted Answer

A) 0.602 N 
B) 1.96 N 
C) 2.41 N 
D) 3.19 N 
E) 4.31 N 
A) 0.602 N 
B) 1.96 N 
C) 2.41 N 
D) 3.19 N 
E) 4.31 N

Question 16

What fraction of the electrons would you have to remove from a 10.0 mg sphere of iron (Z=26,A=56)in order to make its charge 1.00 C?

Accepted Answer

A) 0.224% 
B) 0.482% 
C) 2.24 * 10-4 
D) 4.82 * 10-4 
E) 4.00 * 10-7 
A) 0.224% 
B) 0.482% 
C) 2.24 * 10-4 
D) 4.82 * 10-4 
E) 4.00 * 10-7

Question 17

Two initially uncharged identical metal spheres are connected by an insulating spring (unstretched length 0.75 m).Charge +2q is placed on the first sphere and -q on the second sphere,causing the spring to contract to a length of 0.54 m.Recall that the force exerted by a spring is k$\Delta$x,where $\Delta$x is the change in the spring's length from its unstretched/uncompressed length and k is the spring constant.If the charge q = 2.06 * 10-5 C,what is the spring constant?

Accepted Answer

A) 125 N/m 
B) 187 N/m 
C) 35.0 N/m 
D) 58.3 N/m 
E) 142 N/m 
A) 125 N/m 
B) 187 N/m 
C) 35.0 N/m 
D) 58.3 N/m 
E) 142 N/m

Question 18

Two point charges are placed on two of the corners of a triangle as shown.What is the direction of the force would be felt by a 6.0 µC charge placed at the right angle relative to the horizontal (positive x-axis to the right)?

Accepted Answer

A) -18S1U1P1$\circ$S1S1P0 
B) +18S1U1P1$\circ$S1S1P0 
C) -45S1U1P1$\circ$S1S1P0 
D) +45S1U1P1$\circ$S1S1P0 
E) -85S1U1P1$\circ$S1S1P0 
A) -18S1U1P1$\circ$S1S1P0 
B) +18S1U1P1$\circ$S1S1P0 
C) -45S1U1P1$\circ$S1S1P0 
D) +45S1U1P1$\circ$S1S1P0 
E) -85S1U1P1$\circ$S1S1P0

Question 19

A small ball with a mass of 40 g and a charge of -0.3  $\mu$C is suspended from the ceiling on a string.The ball is suspended a distance of 7.0 cm above an insulating floor.If a second small ball with a mass of 50 g and a charge of 0.6  $\mu$C is placed on the floor directly beneath the first ball,what is the tension in the string?

Accepted Answer

A) 0.04 N 
B) 0.06 N 
C) 0.33 N 
D) 0.39 N 
E) 0.72 N 
A) 0.04 N 
B) 0.06 N 
C) 0.33 N 
D) 0.39 N 
E) 0.72 N

Question 20

A fixed +2.0 mC charge is located at the origin,and a fixed -5.0 mC charge is located at x = 1.0 m.Where could a +7.0 mC charge be placed so that the net force on it is zero?

Accepted Answer

A) -1.7 m 
B) -0.67 m 
C) -0.39 m 
D) +0.39 m 
E) +0.67 m 
A) -1.7 m 
B) -0.67 m 
C) -0.39 m 
D) +0.39 m 
E) +0.67 m

Exam 21: Electrostatics

Find the magnitude and direction of the electrostatic force on the electron in the figure shown.

A glass rod is charged by triboelectric charging and 13 * 1010 electrons removed.What is the charge on the rod?

Two small,charged objects,Q1 and Q2,are some distance d apart from each other and there is a force F between them.What is the value of the force if Q1 is increased by a factor of two,Q2 is increased by a factor of 3,and d is increased by a factor of 5?

A plastic ball of charge -5 nC is held 2 cm above a glass bead of charge +5 nC at rest on a table.For the glass bead to leap up to the plastic ball its mass must be

Find the magnitude of the net force on a 1.20 mC charge at the origin if there is a +2.40 mC charge at (3.0m,0)and a -5.70 mC charge at (0,4.0m).

Three electrons are located at the vertices of an equilateral triangle,one at each vertex.The length of one side of the triangle is 1.00 nm.What is the magnitude of the net electrostatic force on each electron?

Which of the following have a smallest net force?

Two charged particles attract each other with a force

A 3.0 µC charge lies 10.0 cm to the right of a 2.0 µC on the x-axis.What is the magnitude of the force on the 2.0 µC charge?

0.482% of the electrons are removed from a sphere of iron (Z=26,A=56),resulting in a net charge of 1.00 C on the sphere.What is the mass of the iron sphere?

A particle (charge = -15.0 µC)is located on the x- axis at the point x = -25.0 cm,and a second particle (charge = +45.0 µC)is placed on the x- axis at x = +30.0 cm.What is the magnitude of the total electrostatic force on a third particle (charge = -3.50 µC)placed at the origin (x = 0)?

What fraction of the electrons would you have to remove from a 10.0 mg sphere of iron (Z=26,A=56)in order to make its charge 1.00 C?

Two point charges are placed on two of the corners of a triangle as shown.What is the direction of the force would be felt by a 6.0 µC charge placed at the right angle relative to the horizontal (positive x-axis to the right)?

A fixed +2.0 mC charge is located at the origin,and a fixed -5.0 mC charge is located at x = 1.0 m.Where could a +7.0 mC charge be placed so that the net force on it is zero?

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A glass rod is charged by triboelectric charging and 13 * 10¹⁰ electrons removed.What is the charge on the rod?