How are amps related to wattage?

Answer 1

An Amp (ampere) is a unit of measurement for electrical current flow. A Watt is a unit of measurement for electrical power. The relationship between current (Amps) and power (Watts) is generally not well understood.

The power (Watts) generated or transmitted by a system is directly proportional to the current (Amperes), and can be expressed in the following equation:

P = IV

Where:

· P is power in Watts

· I is current in Amperes

· V is voltage in Volts

The 'P=IV' equation is correct for all direct current (DC) circuits and for those alternating current (AC) circuits in which the power factor is 1.

When the current or the voltage is not constant, but varies with time t, the correct equation is:

p (t) = i (t) v (t)

Where:

· p (t) is the instantaneous real power in Watts

· i (t) is the instantaneous current in Amperes

· v (t) is the instantaneous voltage in Volts

P = I*V* pf

where

· P is average power in Watts

· I is RMS current in Amperes

· V is RMS voltage in Volts

· pf is the power factor of the load

When the current or the voltage is a perfect sine wave (which they rarely are),

pf = cosine (angle between the voltage and current)

so

P = I*V* cosine (angle between the voltage and current).

The power (Watts) consumed by a purely resistive system is directly proportional to the square of the current (Amperes), and can be expressed in the following equation:

P = I2R,

Where:

· P is power in Watts

· I is current in Amperes

· R is resistance in Ohms.

The power consumed can be much less than the power transmitted. For example, consider a power cable that carries 1,000 Amps at 100 Volts. The power delivered through the cable (P=IV) is 1,000 x 100, or 100,000 Watts. Let's assume the same power cable has a resistance of 0.001 Ohm (1 Milli Ohm) from one end to the other. The power consumed by that cable (P = I2R, which is the electrical power converted into heat) is 0.001 x 10002, or 1,000 Watts. That means there are only 99,000 Watts available after the current flows through the cable.

Now consider an identical power cable, but this time it carries 100 Amps at 1,000 Volts. The power delivered through the cable (P=IV) is 100 x 1000, or still 100,000 Watts. But this time the power consumed by that cable (P = I2R) is 0.001 x 1002, or 10 Watts. In this case, there are 99,990 Watts available after the smaller current flows though the same cable. This is why electrical power companies transmit high power at such high voltages - to reduce the amount of current flowing through the cables, and thus dramatically reducing the power lost to transmission.

See related links below.

Answer 2

In a simple electrical circuit, watts are equal to the product of voltage and amperage (P = V x I). Amps (amperage) represent the flow of current in the circuit, while watts (wattage) measure the power consumed or produced by the circuit. Increasing amperage while keeping voltage constant will result in higher wattage consumed.

Answer 3

Power equals I2RIn a nutshell, the power (measured in watts) dissipated by a resistance is directly proportional to the square of the current (measured in amperes or amps) flowing through that resistance.

It is given by the formula P = I2R, where P is the power in watts, I is the current in amps, and R is the resistance in ohms. For example, if two amps are flowing through a 10-ohm resistor, then the power dissipated by the resistor is 22 * 10 = 40 watts.

See also the Web Links to the left of this answer for more information.

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Another useful equation that looks less scary, omits resistance and instead uses voltage (E).

P = I X E

That 60W light bulb... assuming it is a 120V bulb and your home voltage is also 120V, would be drawing .5 amps (P/E = I)

Answer 4

Appliances will have either a heating element, an electric motor, or perhaps a transformer to step down the voltage for electronic components. These are usually designed for a given voltage, 110v in N America or 240v in most other countries. If a 110v device is connected to 240v, it will take excessive current and probably be damaged. If the reverse is tried, the 240v device may not work at all on 110v.

By Ohms Law, current = voltage/resistance. So if the voltage is doubled, the current will also be doubled. But wattage = (currentsquared) x resistance, so the wattage would be four times as great, leading probably to overheating.

Answer 5

power = voltage * current

Voltage is an energy force that develops the potential power se can see. You can think of it as a water fall. The higher the waterfall, the longer the trip for a water droplet.

Current is the actual water going over the waterfall. If you have only one drop of wate, not much damage if you stand under it. While Niaigra Falls will leave a mark. Moe wate (current) equals more energy.

Voltage is the potential amount of power while current is the kinetic energy actually happening. A battery has a voltage output even when not connected. It takes flow (a circuit) to make that potential energy useful.

Answer 6

The wattage of the device is the product of the amperage times the voltage of the device. The wattage is what you are billed for by the utility company. The higher the wattage the more the device costs you to operate. You are billed by the kWh, which is 1000 of watts per hour. The average cost per kWh is about seven cents. This means that you can use 1000 watt of power for one hour and it will cost you seven cents.

Answer 7

Energy = power * time. For an electrical appliance, there are three operations: active, idling, and off. The off time is not including in the time factor in the equation. The active power is much higher than the idling power. You can use an energy meter to measure the average power of these two modes. A laptop computer consumes about 50 W of power when running, and 0.5 W during standby. So, Energy consumed in a day may be (8 hrs * 50 W) + (8 hrs * 0.5W), assuming the laptop is running for 8 hours and is on standby for 8 hours. The daily energy consumption for this laptop is 0.4 kW-h.

Answer 8

VA is meant as Apparent Power. Formula = V X A [ Voltage X Current]. Watt is a unit of True power Formula = V X A X Cosθ [ Voltage X Current X Power factor].

Answer 9

That depends on the voltage. Amp is a unit of electric current. Watt is a measure of power.

Power = Current * Voltage --> Current = Power / Voltage.

Answer 10

Watts equals volts times amperes.