Light bulb When switch is closed, bulbs are … Brighter The same Dimmer than the bulb above (?)
When switch is closed, the right bulb will be … Brighter The same Dimmer than the left bulb now (?)
EXAMPLE: What’s the voltage across, and the current thru each resistor? 12V 100 200 (compare with equivalent R method …)
EXAMPLE: What’s the voltage across, and the current thru each resistor?
Electric circuits: Kirchhoff’s Rules start
Electric circuits: Kirchhoff’s Rules start
Electric circuits: Kirchhoff’s Rules start
Electric circuits: Kirchhoff’s Rules start
Electric circuits: Kirchhoff’s Rules start
The height analogy
(weeeee!)
The height analogy
Electric circuits: Kirchhoff’s Rules Rule 1: The sum of voltage drops around a loop is always zero! (Energy conserved)
The voltage divider 1/2 (solve for I ) No numbers yet!
The voltage divider 2/2 (solve for V 1 & V 2 ) No numbers yet!
The voltage divider: Numbers!
Electric circuits: Kirchhoff’s Rules Rule 2: The sum of currents entering a junction must equal the sum of currents leaving it! (comes in = goes out)
Parallel Circuit No numbers yet!
Parallel Circuit Numbers
A not-to-bad example: NY Kirchhoff’s laws step-by-step …
A not-to-bad example: Currents! 1)Guess directions
A not-to-bad example: Currents! 1)Guess directions 2)Use nodes to reduce set
A not-to-bad example: Voltage Loops! Loop ab cd + - -
A not-to-bad example: Voltage Loops! + + ab c d Loop 2
Solve the equations for the currents! No problem here
A not-to-bad example: The Check!
A bad example: + +
I ) Assign currents! + +
+ +
+ +
II ) Look at currents in & out of nodes + +
+ +
III ) Assign voltage differences (drops)
IV ) Loops! Voltage differences must add to zero a bc d
a bc d
V ) Now, solve those currents More space
Now …