How do you read the value of a resistor?
- Position the resistor with the gold or silver color band to the right..
- Read the color sequence that must be decoded to determine resistance.
- Determine the coded number for the resistive value.
- Determine the tolerance of the resistor.
- Determine the decoded number for the resistive value.
If I understand your question, then yes - resistors are reversible, in the sense that they can be connected to the circuit in either direction. Resistors are not like diodes or capacitors. They do not have a polarity. The conduct (or resist) current equally in both directions of current flow.
- Resistors are blind to the polarity in a circuit. Thus, you don't have to worry about installing them backwards. Current can pass equally through a resistor in either direction. In schematic diagrams, a resistor is represented by a jagged line, like the one shown in the margin.
- 4k7 / 4.7k ohm Resistor Colour Code
Value 4.7 kΩ / 4700 Ω Type 4 Band Colour Code Colour Code Yellow, Violet, Red, Gold Multiplier Red, 100 Tolerance Gold Band ±5%
- The large, 20,000 µF electrolytic unit shown in the upright position has its positive (+) terminal labeled with a “plus” mark. Ceramic, mylar, plastic film, and air capacitors do not have polarity markings, because those types are nonpolarized (they are not polarity sensitive).
- Remove power from the circuit containing the resistor.
- Isolate the resistor from the circuit.
- Inspect the resistor.
- Read the resistor value visually.
- Prepare a digital multimeter (DMM) to measure the resistor.
- Measure the resistance.
- Determine the actual resistance of the resistor.
- The range switch sets where the decimal place is located on the display. On the 200 ohm range, full scale will be 199.9 ohms. On the 2K scale, it is 1999 ohms. For 20K, 19.99 K, and 20 Meg, 19.99 meg.
- How to test for continuity
- Turn the dial to Continuity Test mode ( ).
- If required, press the continuity button.
- First insert the black test lead into the COM jack.
- Then insert the red lead into the V Ω jack.
- With the circuit de-energized, connect the test leads across the component being tested.
- To check continuity on a run of wiring, disconnect both ends of the wire. Set your multimeter to check continuity with a tone. Put one meter lead on one end of the wire and the other meter lead on the opposite end of the wire. The meter signals a tone and shows near zero ohms of resistance if the wire has continuity.
Current in the drawing above is shown entering the + side of the resistor. Resistors don't care which leg is connected to positive or negative. The + means where the positive or red probe of the volt meter is to be placed in order to get a positive reading. This is called the "positive charge" flow sign convention.
- The negative pin of the cap is usually indicated by a “-” marking, and/or a colored strip along the can. They might also have a longer positive leg. Below are 10µF (left) and a 1mF electrolytic capacitors, each of which has a dash symbol to mark the negative leg, as well as a longer positive leg.
- Think of a diode as a one-way street for electricity. When the diode is in forward bias, the diode allows traffic, or current, to flow from the anode, towards the cathode leg. In a reverse bias current is blocked so there is no flow of electricity through the circuit.
- Why does electric current always flow from positive to negative? It is said that current flows from positive terminal to negative terminal, but it is actually the negative electrons flowing to positive as the positive electrons don't move.
Updated: 3rd October 2019