# Define the relationship between voltage current and resistance

### Ohm’s Law - How Voltage, Current, and Resistance Relate | Ohm's Law | Electronics Textbook

How electrical charge relates to voltage, current, and resistance. a quick way to reference the relationship between voltage, current, resistance, and power. Ohm starts by describing a unit of resistance that is defined by current and voltage. Current, Voltage, And Resistance Calculations. Current. Current is “the flow of negative charge electrons from one place to another in a conductor”. The current . Originally Answered: What are current, voltage and resistance in simple terms? What is the difference and relationship between the electric current, voltage.

Similarly, if the voltage increases, the current increases. For a constant resistor, if the voltage across it remains unchanged, the current through it remains unchanged. Alternatively, if the current through the resistor does not change, it implies that the voltage across it has not changed. Note that it is always the voltage applied to a resistor that determines how much the current through the resistor is.

If as a result of the generated heat the resistance of the element increases by 10 percent, what current is in the element? Solution Change in the voltage is relatively small, and it does not affect the resistance of the element. If the applied voltage is V instead, what is the current? Solution Although for this problem one can numerically find a value for the new current because the voltage is almost doubled, the physical lightbulb cannot withstand the higher current and its filament will blow.

Measuring Electric Current Any electric circuit has a current in it based on the components in the circuit and based on the voltage of its source. Often, it is necessary to measure the current in a circuit for diagnosing problems and repairs. To measure current in a circuit, an ammeter must be inserted inside the circuit; that is, it must become part of the loop forming the circuit.

## Relationship and Difference Between Voltage, Current and Resistance

Then you connect the two leads of the meter to the open ends of the circuit. In this way, the ammeter integrates to the loop and becomes part of the circuit.

Device to measure electric current. To measure current in a circuit, an ammeter must be inserted inside the circuit. The circuit must be opened for this purpose.

A multimeter is a multipurpose device that can measure current in addition to voltage and resistance. It has the capability to measure additional entities, such as capacitance and frequency.

Note that all the components including the source and wires in a single circuit one loop only have the same current. Device for electrical measurements with selectable switches to function as voltmeter, ohmmeter, and ammeter, and some more capabilities all in the same unit.

Because in DC electrical current has one direction and in AC electric current direction constantly changes, measuring current in AC and DC is not done by the same ammeter. For DC a DC meter must be used. In multimeters switching from AC meter to DC and from current to voltage and so on can be done using a selector switch with which one selects the desired choice. In measuring DC current the red lead of the meter must be connected to the positive side and the black lead to the negative side.

If the leads are switched, the reading will be negative. In some ammeters not multimeters with a needle, the zero point is in the middle and the motion of the needle indicates both positive and negative readings.

This is helpful for the circuits in which current can be either positive or negative. Pay attention for measuring voltage; you should not open the circuit. Whereas for measuring current, one must open the circuit. Thus, the voltmeter is connected at points A and B so that the load is between points A and B Figure 4.

The measured value is the voltage applied to the load. A voltmeter, in fact, measures the voltage difference between two points.

• Ohm’s Law - How Voltage, Current, and Resistance Relate
• Current, voltage and resistance

Note that, whereas in a single one loop circuit there is only one current, there are various voltages depending on the number of components in the circuit and where the measurement is made. The measurement across the source shows the source voltage. Any other point on each line denotes the same point of the circuit. In DC electricity, voltage measurement shows the polarity, too.

So, if the positions of the leads of a meter are swapped, in a digital meter the reading will appear with a negative sign, but in an analog meter, the reading cannot be done because the needle is forced to move to the left. A voltmeter measures the voltage difference between two points by connecting the meter leads to those points. In any measurement, care must be taken that all the connections are clean and tight. This is especially true for the leads of a handheld meter. One coulomb of charge is equal to 6,,, electrons.

Cast in these terms, current is the rate of electric charge motion through a conductor. As stated before, voltage is the measure of potential energy per unit charge available to motivate electrons from one point to another.

### Relationship and Difference Between Voltage, Current and Resistance

Defined in these scientific terms, 1 volt is equal to 1 joule of electric potential energy per divided by 1 coulomb of charge. Thus, a 9 volt battery releases 9 joules of energy for every coulomb of electrons moved through a circuit. These units and symbols for electrical quantities will become very important to know as we begin to explore the relationships between them in circuits. Ohm expressed his discovery in the form of a simple equation, describing how voltage, current, and resistance interrelate: In this algebraic expression, voltage E is equal to current I multiplied by resistance R.

Using algebra techniques, we can manipulate this equation into two variations, solving for I and for R, respectively: In the above circuit, there is only one source of voltage the battery, on the left and only one source of resistance to current the lamp, on the right. In this first example, we will calculate the amount of current I in a circuit, given values of voltage E and resistance R: What is the amount of current I in this circuit? In this second example, we will calculate the amount of resistance R in a circuit, given values of voltage E and current I: What is the amount of resistance R offered by the lamp?

In the last example, we will calculate the amount of voltage supplied by a battery, given values of current I and resistance R: What is the amount of voltage provided by the battery?

The Basics of Voltage, Current and Resistance