Download Electric Fields Test - Westgate Mennonite Collegiate

Knowledge &
Understanding
(Sig Figs/Units, Multiple
Choice, #1 - 5)
19
Scientific Inquiry &
Problem Solving
(#6 - 10)
Communication &
Application
19
Name: __________________________
Grade 11 Physics – Electric Fields Test
You must show all your work for full marks (excluding multiple choice), include
the formula you are using and round answers to the correct sig figs and units.
Multiple Choice: Choose the best answer (1 mark each)
1. If there is a force of 5.0 x 10-12 N [left] acting on an electron, the electric
field at the location will be:
a. zero.
b. 8.0 x 10-31 N/C [left]
c. 3.1 x 107 N/C [left]
d. 3.1 x 107 N/C [right]
2. The electric field lines for the following parallel plates would be directed:
a.
b.
c.
d.
+
+
+
+
-
upward
to the left
to the right
zero, so its direction would be without meaning
3. A physics student, Billy, uses a piece of silk to rub a comb. The comb then
becomes positively charged. The comb is positively charged because it:
a. gains electrons
b. gains protons
c. loses electrons
d. loses protons
L. Mann
PHY30S
4. The diagram shows the electric field lines between two electrical charges P
and Q. Which of the following statements about the charges on P and Q is
correct?
a.
b.
c.
d.
P is positive and Q is negative
P is negative and Q is positive
P and Q are both positive
The charge cannot be determined with only field lines
5. The same physics student, Billy, draws the following diagrams to illustrate
the electric field between two charged objects. Which of them is incorrect?
A
B
D
C
6. Billy now rubs a rubber mat with fur during class and finds out that the mat
becomes negatively charged. What has happened between the mat and the
fur?
a. The protons in the mat are transferred to the fur
b. The electrons in the mat are transferred to the fur
c. The protons in the fur are transferred to the mat
d. The electrons in the fur are transferred to the mat
7. The diagram below shows the electric field lines of a negative point charge.
The strength of the electric field is:
a. The greatest at point P
b. The greatest at point Q
c. The greatest at point R
d. The same at all three points
L. Mann
PHY30S
8. A neutral object loses 3 electrons. What is its charge in Coulombs?
a. -3C
b. -4.8 × 10-19C
c. +3C
d. +4.8 ×10-19 C
9. In a Millikan experiment, an oil drop is balanced between two charged plates
(as shown below). If the oil drop has a positive charge, which must be true:
a. The electric force points down
b. The force of gravity points up
Positive charge
c. The electric field points up
d. The electric field points down
Conversions
1. Convert 3.5 x 10-4 C to e.c. (1 mark)
2. Convert 21.3N/C to N/e.c. (1 mark)
3. An oil drop has a charge of -1.2 x 10-11C
a. Has the oil drop lost or gained electrons? (1 mark)
b. How many electrons has it lost or gained? (1 mark)
L. Mann
PHY30S
Electric Field Lines
4. Draw the electric field diagram for two positive charges (2 marks)
5. For the following electric field, draw the direction a
a. proton would feel a force at point x (1 mark)
b. electron would feel a force at point y (1 mark)
x
y
L. Mann
PHY30S
Electric Fields
6. A +2.0 e.c. charge is placed in an electric field of 1.9 x 1020 N/C [up]. What is the
magnitude and direction of the electric force it feels? (3 marks)
7. An electron is placed in an electric field and feels an electric force of
3.4N [up]. What is the magnitude and direction of the electric field?
(3 marks)
8. Two charged particles are placed in the same electric field, both the same distance away
from the charge creating the field. One particle has a charge of +1.3 x 10-11 C and feels a
force of 2.4N [E]. The other particle has a charge of -2.4 x 10-14 C, what is the magnitude
and direction of the force it feels? (3 marks)
L. Mann
PHY30S
Millikan’s Experiment
9. An oil drop with a mass of 1.22 x 10-14 kg is held in balance between two parallel plates.
The electric field between the two plates is 1.50 x 105 N/C.
a. If the top plate has a negative charge, is the oil drop positively or negatively
charged? Explain. (2 mark)
b. Calculate the charge on the oil drop. (3 marks)
c. Has the oil drop lost or gained electrons? (1 mark)
d. How many electrons has it lost or gained? (1 mark)
L. Mann
PHY30S
Parallel Plates
10. A particle with a charge of +3.11 x 10-12 C is located in an electric field of
4.00 x 10-2 N/C [up] between two parallel plates. The charge is accelerating at 54.3m/s2
[up]. Calculate the mass of the charge. (3 marks)
Correct Sig Figs and Units: There will be 2 marks given for using the correct sig figs and units
throughout the test. There will be 0.5 marks taken off for each mistake, to a maximum of 2
marks. I will not be concerned with the number of sig figs for questions 4, 5, 9(d).
L. Mann
PHY30S