# Voltage and pressure relationship

### Water circuit analogy to electric circuit

The pressure at the end of the hose can represent voltage. The water in . Now we're starting to see the relationship between voltage and current. But there is a. experiments on the relation between current, voltage, pressure, and the length of the dark space were given for the gases hydrogen, nitrogen, oxygen, and air. In a direct current (DC) electrical circuit, the voltage (V in volts) is an Each quantity and each operational relationship in a battery-operated DC circuit has a In the water circuit, the pressure P drives the water around the closed loop of pipe.

And doubling the voltage across a resistor will double the current.

### Voltage Is compared to pressure - Electrical Engineering Stack Exchange

A voltage between a pair of parallel plates creates a certain force, larger for plates with more surface area. This is much like the pressure-difference between two sides of a piston inside a cylinder.

Voltage is also like pressure in that, at a single point, pressure is meaningless, and so is voltage.

In other words, a single point can have many pressures at the same time, depending on which distant point we pick as a reference pressure. And, the voltage on a wire is meaningless, since a wire can have many voltages at the same time, depending on which second wire we choose as our zero-volt reference. Pressure and voltage must be measured between two locations. Of course the pressure-analogy of voltage needs a charged surface, and this shows how voltage differs from pressure: For charge distributed inside a 3D object, voltage can apply a force to the inside of the object and drag the entire charge along.

Pressure only applies a force to a surface, and is proportional to the surface area, and not to the volume or mass. Yes, the unit called "Volt" can be defined as the work done per unit charge.

But be very careful with that. Because Electrical Potentials themselves, "voltages," are quite different: E-fields are not just "work done per unit charge. Defining voltage as "work per unit charge" is like defining "gravity" as just being the work done per kilogram being lifted. Yet if we take away the kilograms of boulder, the gravity and Gravitational Potentials are still there in space! Similarly, in an electrical circuit, the work done to move electrons or other charge-carriers is equal to "electrical pressure" multiplied by the quantity of electrical charges moved.

In relation to "flow", the larger the "pressure difference" between two points potential difference or water pressure differencethe greater the flow between them electric current or water flow. See " electric power ". Working on high voltage power lines Specifying a voltage measurement requires explicit or implicit specification of the points across which the voltage is measured.

When using a voltmeter to measure potential difference, one electrical lead of the voltmeter must be connected to the first point, one to the second point.

## DC Circuit Water Analogy

A common use of the term "voltage" is in describing the voltage dropped across an electrical device such as a resistor. The voltage drop across the device can be understood as the difference between measurements at each terminal of the device with respect to a common reference point or ground.

The voltage drop is the difference between the two readings. Two points in an electric circuit that are connected by an ideal conductor without resistance and not within a changing magnetic field have a voltage of zero. Any two points with the same potential may be connected by a conductor and no current will flow between them.

The various voltages in a circuit can be computed using Kirchhoff's circuit laws. When talking about alternating current AC there is a difference between instantaneous voltage and average voltage. Instantaneous voltages can be added for direct current DC and AC, but average voltages can be meaningfully added only when they apply to signals that all have the same frequency and phase.

Measuring instruments[ edit ] Multimeter set to measure voltage Instruments for measuring voltages include the voltmeterthe potentiometerand the oscilloscope. The voltmeter works by measuring the current through a fixed resistor, which, according to Ohm's Lawis proportional to the voltage across the resistor.

The potentiometer works by balancing the unknown voltage against a known voltage in a bridge circuit. The cathode-ray oscilloscope works by amplifying the voltage and using it to deflect an electron beam from a straight path, so that the deflection of the beam is proportional to the voltage.