You can carry out most calculations involving Watt’s formula manually. W = VI. It defines the relationship between power, voltage and current. Comments. The same also goes for voltage when only current and power are known (V=P/I). According to Ohm’s law, I=V/R and V=IR. The quantity symbol for power is P and is the product of voltage multiplied by the current with the unit of measurement being the Watt ( W ). In this article, we will discuss Watt’s law, its formula, applications, and other related concepts. This law states that the power in a circuit is a product of voltage and current. Simply put, it is the amount of electrical energy transferred per unit time. Tags: electrical theory, reference guides. If you have a power source, you can use this formula to calculate the actual power the source can generate. Watt’s law is named after James Watt, a Scottish engineer and chemist. Power (P) is a measure of the quantity of work a circuit can do, or a component can consume per unit time. The unit of power is joule per second (J/sec) also known as watts (W). V = voltage, electric potential difference Δ V or E = electromotive force (emf = voltage). The voltage V in volts (V) is equal to the current I in amps (A) times the resistance R in ohms (Ω): V (V) = I (A) × R (Ω) The power P in watts (W) is equal to the voltage V in volts (V) times the current I in amps (A): P (W) = V (V) × I (A) AC Ohm's law formula. The watt is named after James Watt, an 18th-century Scottish inventor. For example, if we have an electric bulb installed in a room, the electrical resistance of the bulb can be calculated using P=V. You can also use it to calculate the power requirement of a component. The following are some of the applications of the Watt’s law formula: If you have a power source, you can use this formula to calculate the actual power the source can generate. For three-phase AC circuits where the line to neutral voltage is known, the formula to convert watts to amps is: I (A) = P (W) V L-N(V) × PF × 3. The higher their value or rating in watts the more electrical power they are likely to consume. You can also use it to calculate the power requirement of a component. When designing the wiring of a building, it is necessary to estimate its total power requirement. How to Convert Watts and Ohms to Amps . The watt (symbol: W) is a unit of power.In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer.In SI base units, the watt is described as kg⋅m 2 ⋅s −3. People often ask; what is the difference between Watt’s law and Ohm’s law? Share this page. Its unit is ampere, or “amps” (A). The unit of measure is ohms (Ω). When you know the power and the voltage of an electrical component, you may calculate its current, using Watt’s formula (I=P/V). The formulas derived from the combination of Watt’s law and Ohm’s law can be used to calculate the electrical resistance of a component. These laws enable us to understand the workings of electric circuits and components. P is power in Watts. This law states that the current passing through a conductor is directly proportional to its voltage, i.e., I=V/R. You can calculate the power requirement of a building using Watt’s formula. The power requirement of a building is achieved by calculating the individual power rating of every electrical appliance or component the building will have and adding them up. V = W / I. Ohm’s law specifies the relationship between current, resistance, and voltage. The current I in amps is equal to the power P in watts divided by the voltage V in volts multiplied by the power factor PF multiplied by 3. In the study of electronics, many laws and theories exist. It is a measure of an electrical component’s ability to resist the flow of electrical current. Ohm's law formula. You can also estimate its electricity costs. Photo: Wikimedia. In order for us to fully understand Watt’s law, we need to first discuss the parameters used in defining it which are: Voltage (V) is the electrical potential difference between two points in an electric circuit. Current can only flow when there is a difference in electrical potential. However, you can also use an online Watt’s law calculator. The following are some of the applications of the Watt’s law formula: Assuming the voltage supplied to that room is x volts, and the bulb is rated at y watts, then the resistance, R=x/y2. Any difference in electrical potential causes electrons to flow from a point of higher potential to a point of lower potential. Given the current and the voltage of the source, all you need to do is multiply the values. Ohm's Law Formula Wheel. Ohms Law is used extensively in electronics formulas and calculations so it is “very important to understand and accurately ... or light, or both. Watt's Law is similarly useful in figuring out the relationship between power, voltage and current.