CAPA 1 winter 2014 MOORE
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
1
Notes: 1. To submit a problem, just click the ”Submit” button under it.
The ”Submit All” button is not necessary.
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
2
Four charges Aq,Bq,Cq, and Dq ( q=3.50×10−7 C) sit in a plane at the corners of a square whose sides have length d=62.0 cm, as shown in the diagram below. A charge, Eq, is placed at the origin at the center of the square.
2. A problem accepted as correct by CAPA will be highlighted in green. Once you see this, your problem has been submitted and accepted as correct.
3. If you are trying to obtain the correct number of significant digits, use the ’E’ notation. I.e. 44+56 = 100. is wrong, but 45 + 56 = 1.0e2 is right in the number of significant digits. 4. Use period ”.” to denote decimal point. comma ”,” doesn’t work here.
5. You are encouraged to solve all the problems independently. For questions about the assignment itself, please consult one of your tutors. If you have any questions about the capa system, don’t hesitate to contact [email protected], i’ll be glad to help you.
Good Luck!
Problem 1
DATA: A=6, B=8, C=3, D=4, E=2 a) Consider the charge at the center of the square. What is the net force, in the x-direction, on this charge? (Take the positive x-direction to be to the right) Problem Weight is: 1 You are correct. Your receipt is 151-5470 b) What is the net force, in the y-direction, on the center charge? (Take the positive y-direction to be up) Problem Weight is: 1 You are correct. Your receipt is 151-1639 c) Consider the situation where A, B, C, and D=1, and E=1, and the following statements. Determine if the following statements are True or False.
Choices: True, False. A. The sum of the forces on the center charge in the xdirection does not equal zero. B. If one were to triple the magnitude of the negative charge, the negative charge would not be in equilibrium. C. The equilibrium point at the center is a stable equilibrium for any motion of the negative charge in the line from the center charge and perpendicular to the plane of the square. D. The sum of the forces on the center charge in the ydirection does not equal zero.
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
3
Problem 2
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
4
Three equal charges, Q1 = Q2 = Q3 = 0.40×10−6 C, are located at the corners of an equilateral triangle of side 14.50 cm.
a) Three charges are arranged on a line as shown above. For each statement select true or false. Choices: True, False. A. If Q1 is positive, Q2 is negative and Q3 is positive, then Q2 MIGHT feel a net force to the right. B. If Q1 is negative, Q2 is negative and Q3 is positive, then Q2 MUST feel a net force to the right. C. If Q1 is positive, Q2 is negative and Q3 is positive, then Q2 MUST feel a net force to the right. D. If Q1 is positive, Q2 is negative and Q3 is negative, then Q2 MUST feel a net force to the right. You are correct. Your receipt is 151-3017 b) In the above figure, R=1.5 m, Q1 = 1.22×10−6 C, Q2 = −Q1 and Q3 = −Q1 . Calculate the total force on Q2 . Give your answer with a positive number for a force directed to the right. You are correct. Your receipt is 151-4410 Problem 3
What is the direction of the force acting on charge Q3? Give the answer in terms of the angle theta between the xaxis and the force, measured in a counterclockwise direction. Express the angle in degrees. (Use ”deg” for degrees) You are correct. Your receipt is 151-7669 Problem 4
A charge Q is transferred from an initially uncharged plastic ball to an identical ball 50.00 cm away. The force of attraction is then 43.31 mN. How many electrons were transferred from one ball to the other? You are correct. Your receipt is 151-5126 Problem 5
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
5
The diagram below shows a dipole centered at the origin and along the x-axis. Determine an expression for the total electric field at a point A (r0 = 1.5L,0) in terms of q and L. Calculate the magnitude of the total electric field at A, when q = 2.60×10−7 C and L = 38.8 cm.
y
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
6
Problem 7
What is the magnitude of the electric field at the centre of a square of side 95.00 cm if one corner is occupied by a charge Q1 = = 60.00 µC and the other three corners are occupied by three charges each of charge Q2 ==-20.00 µC. You are correct. Your receipt is 151-4800
(-L,0) O
-q
.
(L,0)
(r,0)
+q
A
c Printed from LON-CAPA MSU
x
You are correct. Your receipt is 151-6761 Problem 6
As shown in the figure, a ball of mass 1.050 g and carrying a positive charge, q = 39.0 µC, is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of θgw = 15.0◦ from the vertical. What is the magnitude of the electric field? 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678
θ
q
uniform E-field
Problem Weight is: 1 You are correct. Your receipt is 151-4017
mg
Licensed under GNU General Public License
1
Notes: 1. To submit a problem, just click the ”Submit” button under it.
The ”Submit All” button is not necessary.
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
2
Four charges Aq,Bq,Cq, and Dq ( q=3.50×10−7 C) sit in a plane at the corners of a square whose sides have length d=62.0 cm, as shown in the diagram below. A charge, Eq, is placed at the origin at the center of the square.
2. A problem accepted as correct by CAPA will be highlighted in green. Once you see this, your problem has been submitted and accepted as correct.
3. If you are trying to obtain the correct number of significant digits, use the ’E’ notation. I.e. 44+56 = 100. is wrong, but 45 + 56 = 1.0e2 is right in the number of significant digits. 4. Use period ”.” to denote decimal point. comma ”,” doesn’t work here.
5. You are encouraged to solve all the problems independently. For questions about the assignment itself, please consult one of your tutors. If you have any questions about the capa system, don’t hesitate to contact [email protected], i’ll be glad to help you.
Good Luck!
Problem 1
DATA: A=6, B=8, C=3, D=4, E=2 a) Consider the charge at the center of the square. What is the net force, in the x-direction, on this charge? (Take the positive x-direction to be to the right) Problem Weight is: 1 You are correct. Your receipt is 151-5470 b) What is the net force, in the y-direction, on the center charge? (Take the positive y-direction to be up) Problem Weight is: 1 You are correct. Your receipt is 151-1639 c) Consider the situation where A, B, C, and D=1, and E=1, and the following statements. Determine if the following statements are True or False.
Choices: True, False. A. The sum of the forces on the center charge in the xdirection does not equal zero. B. If one were to triple the magnitude of the negative charge, the negative charge would not be in equilibrium. C. The equilibrium point at the center is a stable equilibrium for any motion of the negative charge in the line from the center charge and perpendicular to the plane of the square. D. The sum of the forces on the center charge in the ydirection does not equal zero.
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
3
Problem 2
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
4
Three equal charges, Q1 = Q2 = Q3 = 0.40×10−6 C, are located at the corners of an equilateral triangle of side 14.50 cm.
a) Three charges are arranged on a line as shown above. For each statement select true or false. Choices: True, False. A. If Q1 is positive, Q2 is negative and Q3 is positive, then Q2 MIGHT feel a net force to the right. B. If Q1 is negative, Q2 is negative and Q3 is positive, then Q2 MUST feel a net force to the right. C. If Q1 is positive, Q2 is negative and Q3 is positive, then Q2 MUST feel a net force to the right. D. If Q1 is positive, Q2 is negative and Q3 is negative, then Q2 MUST feel a net force to the right. You are correct. Your receipt is 151-3017 b) In the above figure, R=1.5 m, Q1 = 1.22×10−6 C, Q2 = −Q1 and Q3 = −Q1 . Calculate the total force on Q2 . Give your answer with a positive number for a force directed to the right. You are correct. Your receipt is 151-4410 Problem 3
What is the direction of the force acting on charge Q3? Give the answer in terms of the angle theta between the xaxis and the force, measured in a counterclockwise direction. Express the angle in degrees. (Use ”deg” for degrees) You are correct. Your receipt is 151-7669 Problem 4
A charge Q is transferred from an initially uncharged plastic ball to an identical ball 50.00 cm away. The force of attraction is then 43.31 mN. How many electrons were transferred from one ball to the other? You are correct. Your receipt is 151-5126 Problem 5
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
5
The diagram below shows a dipole centered at the origin and along the x-axis. Determine an expression for the total electric field at a point A (r0 = 1.5L,0) in terms of q and L. Calculate the magnitude of the total electric field at A, when q = 2.60×10−7 C and L = 38.8 cm.
y
Mlanie LaRoche-Boisvert - Electromagnetism Electromagnetism and Optics - Winter 2014 - PH
6
Problem 7
What is the magnitude of the electric field at the centre of a square of side 95.00 cm if one corner is occupied by a charge Q1 = = 60.00 µC and the other three corners are occupied by three charges each of charge Q2 ==-20.00 µC. You are correct. Your receipt is 151-4800
(-L,0) O
-q
.
(L,0)
(r,0)
+q
A
c Printed from LON-CAPA MSU
x
You are correct. Your receipt is 151-6761 Problem 6
As shown in the figure, a ball of mass 1.050 g and carrying a positive charge, q = 39.0 µC, is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of θgw = 15.0◦ from the vertical. What is the magnitude of the electric field? 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678 1234567890123456789012345678901212345678901234567890123456789012123456789012345678
θ
q
uniform E-field
Problem Weight is: 1 You are correct. Your receipt is 151-4017
mg
Licensed under GNU General Public License
