# 17 1 current and resistance relationship

### Power's relationship to Resistance - Electrical Engineering Stack Exchange

Ohm's Law. There are 2 base formulae which will help you to understand the relationship between current, voltage, resistance and power. If you have any two of. How electrical charge relates to voltage, current, and resistance. way to reference the relationship between voltage, current, resistance, and power. .. we have a circuit with the potential of 1 volt, a current of 1 amp, and resistance of 1 ohm. The electrical resistance of an object is a measure of its opposition to the flow of electric current. 1 Introduction; 2 Conductors and resistors; 3 Ohm's law; 4 Relation to .. When an alternating current flows through a circuit, the relation between current . page ; ^ The resistivity of copper is about ×10−8 Ωm. See [1].

Materials are important as well. A pipe filled with hair restricts the flow of water more than a clean pipe of the same shape and size.

Similarly, electrons can flow freely and easily through a copper wire, but cannot flow as easily through a steel wire of the same shape and size, and they essentially cannot flow at all through an insulator like rubberregardless of its shape. The difference between copper, steel, and rubber is related to their microscopic structure and electron configurationand is quantified by a property called resistivity.

In addition to geometry and material, there are various other factors that influence resistance and conductance, such as temperature; see below. Conductors and resistors[ edit ] A 6. An ohmmeter could be used to verify this value. Substances in which electricity can flow are called conductors.

## CHAPTER 28

A piece of conducting material of a particular resistance meant for use in a circuit is called a resistor. Conductors are made of high- conductivity materials such as metals, in particular copper and aluminium. Resistors, on the other hand, are made of a wide variety of materials depending on factors such as the desired resistance, amount of energy that it needs to dissipate, precision, and costs. Ohm's law The current-voltage characteristics of four devices: Two resistorsa diodeand a battery.

### Ohm's Law with Calculator

The horizontal axis is voltage dropthe vertical axis is current. Ohm's law is satisfied when the graph is a straight line through the origin. Therefore, the two resistors are ohmic, but the diode and battery are not. For many materials, the current I through the material is proportional to the voltage V applied across it: Therefore, the resistance and conductance of objects or electronic components made of these materials is constant.

This relationship is called Ohm's lawand materials which obey it are called ohmic materials.

## Electrical resistance and conductance

Examples of ohmic components are wires and resistors. The current-voltage IV graph of an ohmic device consists of a straight line through the origin with positive slope.

Other components and materials used in electronics do not obey Ohm's law; the current is not proportional to the voltage, so the resistance varies with the voltage and current through them. These are called nonlinear or nonohmic. Examples include diodes and fluorescent lamps.

### CURRENTS AND OHMS LAW

The combination of the two will result in power dissipation in the speaker's voice coil in the case of audio. Since an amplifier can produce a limited amount of voltage limited by the internal power supply's designthe power output is limited when driving a given load i. To be able to produce more power, you can drive a lower impedance resistance load within reason.

This means that if you go from a 4 ohm load to a 2 ohm load, the power will double assuming that the power supply is regulated.

If we use the example of a watt mono amplifier watts into a 4 ohm loadwe know it can produce no more than 20 volts across the speaker. If you set the voltage slider below to 20 volts, and the resistance slider to 4, you can see that the power is watts.

If you move the resistance slider to 2 ohms, you can see that the power is doubled to watts.

Now, I know that I'm showing a battery as the voltage source instead of an amplifier but the concept is the same. Click HERE to make this applet fill this window. Historical Information Georg Simon Ohm: Georg Simon Ohm was a German physicist that lived from to He found that, with a constant resistance, voltage and current were directly proportional as we showed in a graph above.