Check answers – a few were found to be wrong…possibly reword the definition/law questions.
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Transcript of Check answers – a few were found to be wrong…possibly reword the definition/law questions.
• Check answers – a few were found to be wrong…possibly reword the definition/law questions
Electrostatics JEOPARDY
Powell
100
WilliamsBrownHeadAugustine
200
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400
500
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500
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500 500
A
Balloons X , Y and Z are hanging as shown. Balloon X is positively-charged
Balloon Y ____.
A must be positively-charged
D could be either negatively-charged or neutral
B must be negatively-charged
E could be either positively-charged or neutral
C must be neutral
What is
D. could be either negatively-charged
or neutral?
The charge an electrophorus would gain if the base was made
out of glass.
A
What is
Negative?
The reason that scraps of paper jump up and down and back
up when a charged plastic rod is brought near.
A
What is
The pieces become polarized, are attracted to the rod, and jump up.
When they touch, the charge is transferred to the piece, giving it the same charge. The attraction
stops. When it touches ground, it looses its charge, allowing it to
become polarized again ?
Explanation of the basic process of charging an electroscope.
A
What is
A charged object is touched to the ball of the electroscope. The
charges are transferred andtravel across the bars of the scope, causing it to repel ?
Explanation of how one’s hair raises when you touch the Van
de Graaff generator.
A
What is
Negative charges travel from the Van de Graaff generator onto
one’s body as they try to get asthey try to spread out. When on your hair, they cause it to raise up as they try to repel as far as possible ?
The magnitude of the force of a +25µC charge on a -50µC
charge 20 cm away.
A
+25µC -50µC
22cm
9x109 (50 x 10-6 C) (25 x 10-6 C) Nm2 C2
(.20 m)2
What is
2.81 x 102 N ?
= 2.81 x 102 N
F =k Q1Q2
r2
The magnitude of the force 10 electrons would apply on 4
protons at a distance of 1µm.
AHint…qe=1.6x10-19 C
What is
9.22 x 10-15 N ?
9x109 [10(1.6 x 10-19 C)] Nm2 C2
(1 x 10-6 m)2
[4(1.6 x 10-19 C)] = 9.22 x 10-15 N
F =k Q1Q2
r2
The force applied on the farthest right charge by the other two
charges.
A
+8µC -6µC
7mm 3mm
+5µC
9x109 (8 x 10-6 C) (5 x 10-6 C) Nm2 C2
(10 x 10-3 m)2
= 3.6 x 103 N
What is
2.64 x 104 N left ?
9x109 (6 x 10-6 C) (5 x 10-6 C) Nm2 C2
(3 x 10-3 m)2
= 3 x 104 N
F13 =
F23 =
F23 + F13 = 2.64 x 104 left
F =k Q1Q2
r2
The number of electrons you would need to put on
electrostatic flying boots to make a 70kg person hover at a height of 2 m above a charge of
-50 mC.
A
Ahhh..
I’m flying!
What is
2.38 x 1012?
F = 70kg (9.81 m/s2) = 9x109 (-50 x 10-3 C) [n(-1.6 x 10-19 C)]
Nm2 C2
(.20 m)2
n = 2.38 x 1012
F =k Q1Q2
r2
The force on the orange charge.
A
+4.6 C
-5.4 C +4.6 C
-5.4 C
5 m
4 m
2.5 m
2 m
+ 7.2 C
What is
0 N ?
Diagonal forces cancel each other out, resulting in a net force of 0N on the orange charge.
F =k Q1Q2
r2
No net electric charge can be created or destroyed.
A
What is
The law of conservation of electric charge ?
+1.6 x 10-19 C
A
What is
The Charge of a proton ?
The charging of an isolated conducting object by grounding
it while a charged body is nearby.
A
What is
Induction ?
The force F exerted on a tiny positive test charge placed
divided by the magnitude of the test charge.
A
What is
Electric Field, E ?
E = F
q
Two equally charged charge that have the opposite charge.
A
What is
A dipole ?
A
The charge of the orange charge
Followed by
The charge of the blue charge
What is
Positive (orange), negative (blue) ?
A
|Q|=4.7 x 10-4 C
Charge on the blue charge
What is
-3.5 x 10-4 C ?
4.7 x 10-4 C
?=
8 lines
6 lines
|Q|=4.7 x 10-4 C
A
The number of lines that should point outwards from
the orange plate.
BE CAREFUL!!!!
?
?
What is
0 ?
Follow up question
How many lines should point inwards?
8 lines8 charges =
?6 charges
A
Charges of point charges in order (orange, blue, green, white)
What is
- - + + ?
Orange
Blue
Green
White
Minimum of 2 errors in the following drawing, with
explanations of error.
A
2 C2 C
What are
Wrong direction of field lines (should go from positive to
negative) and
Wrong number of field lines (should be equal as charge is
equal) ?
E-Field at X below
A
12 C
15m
What is
6 x 108 N/C left ?
12 C
15m
9x109 (12 C) Nm2 C2
(15 m)2
= 6 x 108 N/C
E =k Q
r2
A
Approximate location of E=0 N/C on line between orange and blue
charge
12 C
15m
24 C
What is
Somewhere between orange and mid point (7.5m to the right of
orange) ?
12 C
15m
24 C
E =k Q
r2
The E-Field at the X
A
12 C
15m
24 C
10 m
What is
2.33 x 109 N/C right ?
E =k Q
r2
12 C
15m
24 C
10 m
E24CE12C
9x109 (12 C) Nm2 C2
(25 m)2
= 1.7 x 108 N/C
9x109 (24 C) Nm2 C2
(10 m)2
= 2.16 x 109 N/C
The letter which denotes the location with the greatest
magnitude of E-Field
A
AB C D
1m4m 3m 2m
Q=1.5C Q=24C Q=18C Q=7C
What is
C ?
E =k Q
r2
EA =k (1.5C)
(1m)2=1.5k C/m2
EB =k (24C)
(4m)2=1.5k C/m2
EC =k (18C)
(3m)2=2k C/m2
ED =k (7C)
(2m)2=1.75k C/m2
A
The E-Field at the orange point.
-4 C
-5 C +4 C
-5 C
5 m
5 m
2.5 m
2.5 m
2.5m
2.5m3.53m=r
E =k Q
r2
9x109 (4 C) Nm2 C2
(3.53 m)2
= 2.89 x 109 N
What is
5.77 x 109 N 45 degrees N of W ?
FINAL JEOPARDY
The complete process for charging an electrophorus using proper terminology.
(5 minutes)
TIE BREAKER
WHAT IS THE SIGNIFICANCE OF THE CATEGORY TITLES?
2004 Illini Basketball Starters(when we should have won the
NCAA tourney)