Download P142_Lect3

A hydrogen atom is composed of a nucleus containing a
single proton, about which a single electron orbits. The
electrical force between the two particles is 2.31039
greater than the gravitational force!
If we adjust the distance separating the two particles,
can we find a separation at which the electrical and
gravitational forces are equal?
1) Yes, by moving the particles farther apart.
2) Yes, by moving the particles closer together.
3) No, at any distance.
Where is the net electric field between
these two charges ZERO?
+16mC
3 meters
+4mC
Where is the net electric field between
these two charges ZERO?
+16mC
3 meters
+4mC
Where is the net electric field between
these two charges ZERO?
+16mC
+4mC
3 meters
d
Where is the net electric field between
these two charges ZERO?
+16mC
+4mC
3 meters
3 meters - d
d
Where is the net electric field between
these two charges ZERO?
+16mC
+4mC
3 meters
3 meters - d
6
d
6
16  10 C
4  10 C
Etotal  k

k
2
2
(3 meters  d )
d
0
6
6
6
6
16  10 C
4  10 C
0k

k
2
2
(3 meters  d )
d
16  10 C
4  10 C
k
k
2
2
(3 meters  d )
d
6
6
16  10 C
4  10 C
0k

k
2
2
(3 meters  d )
d
6
6
16  10 C
4  10 C

2
2
(3 meters  d )
d
4
1

2
2
(3 meters  d )
d
2
1

(3 meters  d ) d
2
1

(3 meters  d ) d
2d  (3 meters  d )
d  1 meter
+16mC
+4mC
3 meters
3 meters - d
d
4 discrete charges of magnitude, q, and the indicated signs,
occupy the corners of
a rectangle as shown.
q
+q
The direction of the
electric field, E , at
the point shown is:
1)
2)
3)
4)
5)
1
up
left
right
down
other
2
3
4
+q
q
4 discrete charges of magnitude, q, and the indicated signs,
occupy the corners of
a rectangle as shown.
q
+q
The direction of the
electric field, E , at
the point shown is:
1)
2)
3)
4)
5)
1
up
left
right
down
other
2
3
4
+q
q
4 discrete charges of magnitude, q, and the indicated signs,
occupy the corners of
a rectangle as shown.
q
+q
The direction of the
electric field, E , at
the point shown is:
1)
2)
3)
4)
5)
up
left
right
down
other
1
+q
q
2
3
4
+

+2q
-q
+2q
-3q
http://unlhep2.unl.edu/~DCLAES/P142_Lect3extras.ppt
Proportionalities
B
A
w
D
y
C
A
 ?
z
1.A/w
2.A/x
3.B/x
4.C/x
5.D/x
6.D/w
x z
Proportionalities
B
D
A
E
C
A
 ?
C
1.E/F
2.F/E
3.D/F
4.F/D
5.E/D
6.D/E
F
Proportionalities
A
r
R
A
 ?
a
1. R-r
2. R+r
3. R2/r2
4. R2/r
5. R/r
6. r/R
a
Proportionalities
A
r
R
A
 ?
a
1. R/r
2. R/r
3. R2/r2
4. R2/r
5. R/r
6. r2/R2
a
The same proportionalities work for arc-lengths
S
r
R
S
R

s
r
s