What is Electromotive Force (EMF)

What is electromotive force (EMF)The electromotive force, EMF shortly, appears within the source of current when current is absent in the circuit, that is when the circuit is unlocked. At free running, that is when the current is absent in the circuit the EMF equals the voltage difference on the clamps of the energy source. The EMF is measured in volts like the voltage difference. The electrical circuit being both locked and unlocked the EMF constantly supports the voltage difference on the clamps of the energy source. For the current to flow continuously within the locked circuit the charges within the current source have to move in the direction, opposite to the direction of the field forces. The transfer of charges is caused by energy, produced by the current source, so that the EMF equals the energy transmitted by the current source to the single positive charge. If the current source transmits the A energy to the electric quantity Q we may calculate the EMF of the energy source by dividing A by Q. The A energy equals capacity multiplied by time and electric quantity Q equals current force multiplied by time, the relationship between the capacity of the current source to the force of current may be called the electromotive force. Trace the EMF by connecting a source of energy to the poles by means of a voltmeter. The voltmeter pointer will deviate to a certain angle. The higher the energy source EMF, the higher the deviation. However, the voltmeter does not show the EMF value. As you see below, the voltage on the current source clamps is measured in volts as is the EMF. High voltage and the EMF are measured in kilovolts, low values of voltage and the EMF are measured in millivolts.