1.10. DC Electrical Circuit Fundamentals
The basic components used here are resistors and power supplies. The power supply provides energy to
the circuit and the simplest power supply is a battery. Resistors are material that limit the amount of
current follow.
This section discusses the generation and sensing of logic “1” which is typically equal to 3.5 and 5 volts.
On the other hand, logic “0” is typically less than 0.7 volts.
Electrical Resistance
Resistor Symbol Resistance is the capacity of a material to impede the flow of current (electric charge). The
most common use of resistors is to limit current flow. The flow of current through a resistor will convert electrical energy to thermal energy.
In some applications, this property is desirable and in other application it is undesirable. Here
are examples of each:- Undesirable: transmission line, digital devices
- Desirable: heater, toaster. oven, stove top
Resistance, R, is a basic ideal element so it is defined in term of current, I, and Voltage.
Ohms law: V = I * R where:- R value is in Ohms or Ω
- V is in volts
- I is in Amperes
Power
Power is measured in Watts and can be calculated using the following equations.
P= V^2 /R = I^2 *R where
V is the voltage and is in volts
I is the current in Amps
R is the resistance in Ohms Example
Find the value of the resistance ,R, and the power consumed by the resistor if Vg = 1 kV and Ig =
5 mA.