### Resistors - A simple circuit

The first analysis we will do is as promised, simple. But we can demonstrate and reinforce a few extremely important fundamental principals here. Remember, the idea behind this website is for students to learn the practical aspects of electronic theory. We all remember from school the rules related to series and parallel resistors. Using ohms law we can calculate the following:

The current flow through R3 never changes and will always be 10ma. This is simply I=E/R or I = 10/1000 or .01 which equals 10ma.

The voltage drop across R3 = 10V always, regardless of the positions of SW1 and SW2.

**SW1 Open and SW2 Open: **

Total current flow = 10ma

Voltage Drop across R1 = 0V

Voltage Drop across R2 = 0V

Voltage measured from Ground to the point where R1 and SW1 are connected together = 10V Voltage measured from Ground to the point where R2 and SW2 are connected together = 0V Current Flow through R1,R2 and R4 = 0ma

**SW1 Closed and SW2 Open
**Total current flow = 15ma

Voltage Drop across R1 = 5V

Voltage Drop across R2 = 0V

Voltage Drop across R4 = 5V

Voltage measured from Ground to the point where R1 and SW1 are connected together =5V

Voltage measured from Ground to the point where R2 and SW2 are connected together = 5V Current Flow through R1 and R4 = 5ma

Current Flow through R2 = 0ma

**SW1 Open and SW2 Closed**

Total current flow = 15ma

Voltage Drop across R1 = 0V

Voltage Drop across R2 = 5V

Voltage Drop across R4 = 5V

Voltage measured from Ground to the point where R1 and SW1 are connected together =10V

Voltage measured from Ground to the point where R2 and SW2 are connected together = 10V

Current Flow through R1 = 0ma

Current Flow through R2 and R4 = 5 ma

**SW1 Closed and SW2 Closed**

Total current flow = 16.77ma

Voltage Drop across R1 = 3.3V

Voltage Drop across R2 = 3.3V

Voltage Drop across R4 = 6.7V

Voltage measured from Ground to the point where R1 and SW1 are connected together =6.7V

Voltage measured from Ground to the point where R2 and SW2 are connected together = 6.7V

Current Flow through R1,R2 and R4 = 16.7 ma

The principals shown here are very basic. I have found many times though in working with technicians, a tendency to over complicate circuits like this. For example, you may want to factor some change in current through R3 when you throw the switches when in fact nothing changes. The reason is that R3, is connected to VCC and Ground, a power supply that in all properly designed electronic circuits have more than enough capacity to supply power to all circuits.

In summary, I hope I have not made any errors in this submission. Secondly, I hope that if anyone reading this finds any error or has a question, they will submit for discussion.