In simple DC Circuits i.e., electric circuits with DC power supply, the power formula is given below: Let us now see different electric power formulas in both DC and AC Circuits. Electric Power Formula in AC & DC Circuitsĭepending on the type of current in the circuit i.e., Alternating Current or Direct Current, the Electric Power can be further classified into AC Power and DC Power. The first term (W/Q) represents the electric potential (V) while the second term (Q/t) represents the current (I). Using the above statement, we can rewrite the previous power equation as: We know that the Electric Potential is the amount of Work done in moving a unit charge and current is the rate of movement of charge. So, if P is the Power, W is the Work and t is the time, then In terms of Physics, Energy is the ability to do Work and the rate of doing that Work is known as Power. Our utility company supplies this electrical energy in the form of electric potential and current and the rate at which electrical energy transfers in an electrical circuit is known as Electrical Power.
Metals conduct very well but materials such as ceramics or glass do not usually conduct electricity at all and are known as insulators.Īnimals contain a high proportion of liquid that will conduct electricity well however skin, fat, bone and hair are poor conductors. Different materials also have different abilities to conduct electricity. The larger the cross-section of a conductor, then the lower its resistance: overhead power cables have a much lower resistance than a lamp flex of the same length. The longer a conductor, the greater its resistance for example, a two metre wire has twice the resistance of a one metre wire of similar properties. The overall resistance of an object depends on a number of properties including its length, cross-sectional area and the type of material. Similarly, the water pressure at (A) will be less than at (B). There will be a drop in voltage due to the energy used up in driving the current through the light bulb, which has a higher resistance than the wire in the circuit. The ammeter is equivalent to the flow meter and the voltmeter measures the difference in electrical pressure each side of the restriction in the water system. In the electrical circuit the power supply generates electrical pressure (voltage), equivalent to the pump creating water pressure in the pipe the current is equivalent to the rate of flow of water and the light bulb provides the resistance in the same way as the restriction in the water system. The flow of electricity through this circuit is further illustrated by analogy to the pressurized water system in Figure 1b. To increase the current flowing in a circuit, the voltage must be increased, or the resistance decreased.Ī simple electrical circuit is depicted in Figure 1a. Ohm’s Law: Current (I) = Voltage (V) / Resistance (R) This states that the current flowing in a circuit is directly proportional to the applied voltage and inversely proportional to the resistance of the circuit, provided the temperature remains constant. The relationship between current, voltage and resistance is expressed by Ohm’s Law. Resistance to alternating current is more properly called impedance but, in this application, resistance and impedance can be considered to be equivalent. The property of a material that limits current flow is known as its resistance (R), the unit of resistance is the ohm (Ω). The driving force (electrical pressure) behind the flow of a current is known as the voltage and is measured in volts (V) (Voltage may also be referred to as the potential difference, or electromotive force). It is measured in amps (A) if the current is very small then it is described in milli-amps (mA), 1000 mA = 1A. The flow of electricity through an object, such as a wire, is known as the current (I).