Electrical Theory & Mathematics

Related Courses

Key Questions

The following key questions are answered in this module:

What are the five key electrical terms for understanding electrical theory?
The five key terms are voltage, current, resistance, reactance, and impedence.

What is Ohm's Law?
Ohm's Law states that the current passing through a conductor between two points is directly proportional to the voltage across those two points. In equation form, it's I = E/R. Rewriting to solve for voltage, E = IR, and to solve for resistance in ohms, R = E/I. E = voltage, units in volts, I = amperage, units in amps, R = resistance, units in ohms, P = power, units in watts

What is Watt's Law?
Watt's Law is similar to Ohm's Law, whereas Watt's Law states the relationship between Power in watts, current, and voltage. In its equation form, it's P = I x E. Using Ohm's Law to substitute the value of E, Watt's Law can also be written as P = I2R.

What is Kirchoff's Law?
Kirchhoff's Law includes Current Law and Voltage Law, and basically states that the algebraic sum of all currents entering and leaving a node on a circuit must be equal to zero (Current Law), and the algebraic sum of all voltages within a circuit loop must be equal to zero (Voltage Law)

What is Faraday's Law?
Faraday's Law pertains to magnetic fields in circuits. The law states that an induced electromotive force (EMF) in any closed circuit is equal to the negative of the time rate of change of the magnetic flux enclosed by the specific circuit. In equation form, it's E = dB/dt, or change in magnetic flux (B) divided by change in time. In other words, the larger the change in the magnetic field, the larger the voltage value.

Sample Video Transcript

Below is a transcript of the video sample provided for this module:

Kirchhoff’s Law includes Current Law and Voltage Law, and basically states that the algebraic sum of all currents entering and leaving a node on a circuit must be equal to zero (Current Law), and the algebraic sum of all voltages within a circuit loop must be equal to zero (Voltage Law). {show image KVL} For current at any specific node on a circuit, it’s also stated as Current In = Current Out. Faraday’s Law pertains to magnetic fields in circuits. Basically, the law states that an induced electromotive force (EMF) in any closed circuit is equal to the negative of the time rate of change of the magnetic flux enclosed by the specific circuit. In equation form, it’s E = dB/dt, or change in magnetic flux (B) divided by change in time. In other words, the larger the change in the magnetic field, the larger the voltage value. Faraday’s Law of induction is a law regarding electromagnetism. It predicts how a magnetic field will interact with electric circuits, and thus produce electromotive forces (EMF). This is the main operating principle of transformers, electrical motors, and generators. It shows that when a conductor is moved through a magnetic field, magnetic flux is induced in a circuit. Another example of this is in capacitors. Capacitors are designed to store energy in the form of an electrical charge. Capacitance is the ratio of stored electrical charge to the potential difference in volts. The units of measure for capacitors are microfarads. When AC electrical current flows through a capacitor, the capacitor will produce a reactance similar to a resistance, and this reactance also resists the current. So, every component in an electrical circuit has some capacitance. The goal of electrical designs is to reduce unwanted capacitance to a minimum.