# 19.1

## The Formulas: $R = \frac{V}{I}$
R=Resistance (ohms)
V=Voltage (Volts)
I=Current (Amps) $P =VI = I^2R = \frac{V^2}{R}$
R=Resistance (ohms)
V=Voltage (Volts)
I=Current (Amps)
P=Power (Watts)

## Series Circuit

### Begin with finding the current:

I=V/R
I=13/(2.4+1.3+6.1+3.4)
I=.9848
store the current, .9848A, in A on your calculator

To find the current running through the ammeters notice that the current can only flow one way through the battery.
Therefore, the current through both ammeters is the same as the current flowing through the entire battery.

V=(I)(R)
V1=?
I=A=.9848A
R=2.4ohms

V1=(A)(2.4)
V1=2.36V

### To find V2:

V=(I)(R)
V2=?
I=A=.9848A
R=6.1+3.4=9.5ohms

V2=(A)(9.5)
V2=9.356V

### To find V3:

V=(I)(R)
V3=?
I=A=.9848A
R=0 ohms (there is not a resistor in this chunk of the battery, therefore the resistance is 0 ohms)

V3=(A)(0)
V3=0V

### To find the greatest power dissipated by a resistor:

P=(I^2)(R)
P=?
I=A=.9848A
R= 6.1 ohms (on a series circuit to find the greatest power you use the circuit with the greatest resistance and to find the least power you use the circuit with the smallest resistance)

P=(A^2)(6.1)

## Parallel Circuit First off, you need to find the currents flowing through each piece of the parallel circuit. The different sections of the circuit are defined with the different colors of current flowing through each resistor; blue, green, and red.

I=V/R
I1=?
V=45V
R=2.1 ohms

I1=45/2.1
I1=21.428A (store I1 in alpha A)

### Next is the green current (I2)

I=V/R
I2=?
V=45V
R=5.6 ohms

I2=45/5.6
I2=8.0357A (store I2 in alpha B)

### Last is the red current I3

I=V/R
I3=?
V=45V
R=4.1 ohms

I3=45/4.1
I3=10.975A (store I3 in alpha C)

The next step is to determine what currents flow through each meter. This is really easy with the lines of color because if the line passes through the meter you add those currents together and you will have the total current through that meter.

The blue, green, and red currents flow through A1, therefore add all of the currents you just found (I1, I2, and I3) together.

A1=A+B+C (keep in mind that you stored the currents in these letters, so use the letters to keep the number accurate, plus it's easier!)

### Next is meter A2:

The green and red currents flow through A2. Therefore add the currents you just found for I2 (green) and I3 (red).

A2=B+C

### Last is meter A3:

If you look at A3 there is only the green (I3) current flowing through the meter. Therefore, the current for I3 is your answer.
A3=C