1. A B C Which of the circuits shown above are wired in parallel?
1) A only
2) B only
3) C only
4) B and C
5) all of them

2. A B C Which of the circuits shown above are wired in parallel?
1) A only
2) B only
3) C only
4) B and C
5) all of them
When resistors are in parallel, the voltage drop across each is the same.

3. What is the current at point P? A) 2 A B) 3 A C) 6 A D) 10 A
E) need more info to answer

4. I1 = I2 + I3 IC = IA + IB Kirchhoff’s Rules (rules of thumb) I1 I2 IB
The SUM OF CURRENTS entering any junction
equals the sum of all currents leaving. I1 I2 IB
I1 = I2 + I3 I3 IC IA
IC = IA + IB
This follows from Conservation of Charge!

5. +24v – 24v = 0 When fully charged at Q=CV=(12pF)(24v) the circuit has
two competing
voltage steps:
+24v – 24v = 0
24 volts

6. 12 V The voltage drop is 6  12  3  greatest across R1.
4. the same across each of the three resistors.

7. The current through the 2 resistor is
4 
2 
12 V
The current through the 2 resistor is
half the current through the 4.
the same as thru the 4.
twice the current through the 4.

8. The current through the 2 resistor is
4 
2  I
12 V
The current through the 2 resistor is
half the current through the 4.
the same as thru the 4.
twice the current through the 4.
½ Ampere Ampere
2 Ampere Ampere
Ampere Ampere

9. What is the “VOLTAGE DROP” across each resistor?
4 
2  I
12 V
The current through the 2 resistor is
half the current through the 4.
the same as thru the 4.
twice the current through the 4.
½ Ampere Ampere
2 Ampere Ampere
Ampere Ampere
What is the “VOLTAGE DROP” across each resistor?

10. V = + 12 V – 8 V – 4 V = 0  Current in each resistor?
Total resistance = 6 
Ohm’s Law: I = V / R
= 12 V / 6 
= 2 A
–IR = –8 V
–IR = – 4 V
4 
2  I
12 V
Voltage drop across a resistor?
V = I R
+ = 12 V
Start
V =
+ 12 V
– 8 V
– 4 V = 0 

11. e Kirchhoff’s Rules (rules of thumb) = IR1+ IR2 + IR3 + IR4 or
2. The SUM OF POTENTIAL DIFFERENCES across
all components of ANY closed circuit loop is ZERO. R1 R2
= IR1+ IR2 + IR3 + IR4 or
- IR1 - IR2 - IR3 - IR4 = 0 e R3 R4
This follows from Conservation of Energy!