1. 6575 6575 Fill in this call number for our section: No. No.
UNIVERSITY OF NEBRASKA-LINCOLN
No.
No.
6575

2. I = V/R The switch is closed on this simple
circuit of an electromagnet: + -
What might affect how rapidly current
reaches its maximum value?
I = V/R
time switch
is closed
time

3. Petrus van Musschenbroek
Leyden, Holland (1746)
Petrus van Musschenbroek

4. The Leyden Jar
capacitor + -

5. Discharging through an inductor should slow the process down:
The act of discharging through
an inductor creates a
short-lived electromagnet.
But rather than vanishing immediately
the strength of the electromagnet
fades slowly as an induced voltage
tries to sustain the current a little longer!
Remember the inductor slows down both
turn-on and the turn-off.

6. I I I + + + + – – – – I + + – – I Fully charged capacitor Current
– – – –
Fully
charged
capacitor I I
+ +
– –
Current
starts
to flow I
Maximum
positive
current I
Maximum
current I

7. Current begins to die down Capacitor fully charged
– –
+ + I
Capacitor fully charged
– – – – I I
– –
+ + I
Current flows
(opposite direction!)

8. Oscillators + + + + – – – – + + – – I I I – – + + I – – – – + + + +
Fully charged capacitor
Energy: all E
Current starts to flow
Energy: some E, some B
– – – –
+ +
– – I
Current begins to die down
induced  
C charges in opposite direction
Energy: some E, some B
Maximum current
Energy: all B I I
– –
+ +
Current flows
(opposite direction!)
Energy: some E, some B
Capacitor charged
Energy: all E I
– – – –
– –
+ +

9. Transmitting antenna “Oscillator” The “tank circuit”
the text talks about

10. Receiving antenna tunable oscillator
“variable
capacitor” to
speakers
tunable
oscillator

11. induction
coil
variable capacitor

12. 2.45 GHz Frequency  1 size of size of inductor capacitor
A small surface
area capacitor
A single loop:
A specially shaped metal “C”:
tiny
capacitor
++++
small
inductance
coil
2.45 GHz

13. A microwave’s MAGNETRON ++++ - - - - - - - - ++++ - - - - ++++ - - - -

14. E B c Recall: the water molecule is slightly “polar” - + + + -
it has “sides”
that are
oppositely charged +

16. - + tungsten heating filament - - - - -- + + + + + + + + accelerated
- -
- - -- +
accelerated
electrons
slam into
the “anode”
+ +
+ +
+ +
+ +

17. - + A B C In which direction are the generated
x-rays most likely to be traveling? -
- -
- - -- + A
+ +
+ + B
+ +
+ + C