Resistor.docx

RESISTOR 1. Pengertian A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. 2. Symbol resistor 3. SI unit The ohm (symbol: Ω) is the SI unit of electrical resistance, named after Georg Simon Ohm. Since resistors are specified and manufactured over a very large range of values, the derived units of milliohm (1 mΩ = 10−3 Ω), kilohm (1 kΩ = 103 Ω), and megohm (1 MΩ = 106 Ω) are also in common usage. 4. Hukum Ohm Ohm's law The behaviour of an ideal resistor is dictated by the relationship specified by Ohm's law: V=I.R Ohm's law states that the voltage (V) across a resistor is proportional to the current (I), where the constant of proportionality is the resistance (R). For example, if a 300 ohm resistor is attached across the terminals of a 12 volt battery, then a current of 12 / 300 = 0.04 amperes flows through that resistor. Practical resistors also have some inductance and capacitance which affect the relation between voltage and current in alternating current circuits. 5. Type a. Linear Resistor Those resistors, which values change with the applied voltage and temperature, are called linear resistors. In other words, a resistor, which current value is directly proportional to the applied voltage is known as linear resistors. Generally, there are two types of resistors which have linear properties 1.

Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. - Carbon composition - Wirewound - Carbon Film - Metal Film 2. Variable resistors can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity. - Potensiometer - Rheostat - Trimpot b. Non linear resistor

We know that, nonlinear resistors are those resistors, where the current flowing through it does not change according to Ohm’s Law but, changes with change in temperature or applied voltage. In addition, if the flowing current through a resistor changes with change in body temperature, then these kinds of resistors are called Thermisters. If the flowing current through a resistor change with the applied voltages, then it is called a Varistors or VDR (Voltage Dependent Resistors). 1. Thermistors 2. Photo Resistor LDR 3. Surface Mount (SMD) 6. Resistance

7. How to use In order to use a resistor you first need to check its effect in a circuit. The drop in voltage inside a circuit can be calculated using the Ohm’ law which is V=IR where V stands for drop in voltage, I stands for the current inside the circuit and R stands for the resistance of the resistor. In order to control the voltage the resistor needs to be on each side of the electrical component later the resistance of the resistors needs to be identified with the help of the color coding method. Components that are sued by students generally has for band color schemes, the four band identification systems needs to be studied as the color of all the four bands are painted on the resistor in order to provide the resistance in Ohms. Resistors in Series: The current inside the resistor flows from one to another and thus they can be connected in series. Here the resistors are arranged in chain so that the current just has a single path to take. The current in series of resistors is the same and the total resistance of a circuit is calculated by adding up the resistance value of the individual resistors. Equivalent resistance of resistor in series is: R= R1 + R2 + R3. It just provides one route for the current to flow inside the circuit. Resistors in Parallel: In this If more than two elements are connected in a parallel way they have same potential difference in their ends. They are the same in magnitude and also have identical polarity. The voltage level is same to all the circuit elements that are connected in a parallel way. Thus the total current is the sum of all the currents through the individual element. Equivalent resistance of resistors in parallel is: (1/R) = [(1/R1)+(1/R2)+(1/R3)].