Introduction to electromotive force
Electromotive force is the physical quantity that reflects the ability of a power source to convert other forms of energy into electrical energy. The electromotive force causes a voltage across the power supply. In the circuit, the electromotive force is usually expressed by E. The unit is volt (V).
Inside the power supply, the non-electrostatic force moves the positive charge from the negative plate to the positive plate. The physical process of doing work is the essence of the power supply electromotive force. The work done by non-electrostatic forces reflects how much other forms of energy become electrical energy. Therefore, in the power supply, the process of non-electrostatic force work is a process of mutual energy conversion.
The magnitude of the electromotive force is equal to the work done by the non-electrostatic force to move the unit positive charge from the negative pole of the power supply to the positive pole of the power supply. If W is the ratio of the amount of work done by the non-electrostatic force (power supply) in the power supply to the amount of charge transferred from the negative electrode through the power supply to the positive terminal of the power supply, the magnitude of the electromotive force is: For example, the electromotive force is 6 volts, indicating that the power supply moves the positive charge from the negative electrode from the negative electrode to the positive electrode through the internal circuit to the positive electrode. Other forms with 6 joules can be converted to electrical energy.
The direction of the electromotive force is defined as the positive pole from the negative pole of the power source passing through the inside of the power source, that is, the direction opposite to the voltage across the power source.