Fundamental Electrical Principles Flashcards
What is Ohm’s Law?
V = I R
Relates voltage (V), current (I), and resistance (R). States that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance.
What does Kirchhoff’s Current Law state?
The sum of currents entering a node equals the sum of currents leaving it.
What is Kirchhoff’s Voltage Law?
The sum of all voltages in a closed loop equals zero.
What does Faraday’s Law of Electromagnetic Induction describe?
An electromotive force (EMF) is induced in a conductor when the magnetic flux linking with it changes. Meaning that a chnage in magnetic field within a closed loop induces and EMF or voltage?
Moving a magnet near a coil will induce a current suggesting a changing magnetic field induces electricity
What is the relationship described by Faraday’s Law regarding induced voltage?
The rate of change within magnetic flux is proportional to induced voltage.
List three applications of Faraday’s Law.
- Transformers
- Electric generators
- Induction motors
What does Lenz’s Law state?
The direction of the induced current opposes the change causing it.
Induced current goes against the change in flux! You can not just carry on creating energy
List three applications of Lenz’s Law.
- Transformers
- Electric generators
- Induction motors
What does Coulomb’s Law describe?
The electrostatic force between two charges (q1 and q2).
This refers to the forces of attraction and repulsion and the magnitude and direction of there application
Think of how negative electrons repel each other. If they are close they force of repulsion would be large, the further away the less the force would be
How is the electrostatic force described by Coulomb’s Law calculated?
Directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
The closer they are the larger the force! Further away the less
What is Ampere’s Law
The integrated magnetic field around a closed loop to the electric current passing through the loop
Running a cable Parallel will cause them to attract! Current in cables running different directions will cause them to repulse
Amperes law shows that the stronger the current through a wire the stronger the magnetic field generated through the loop of the cable!
What does Gauss’s electric Law describe?
The electric flux through a closed surface being proportional to the charge enclosed.
What does Gauss’s Law state about magnetic flux through a closed surface?
The total magnetic flux through a closed surface is always zero.
What does the absence of magnetic monopoles imply?
Magnetic poles always come in pairs (north and south).
What is the behavior of magnetic field lines?
Magnetic field lines always form continuous loops.
What is Thevenin’s Theorem?
Any linear circuit can be replaced with an equivalent circuit containing a single voltage source and a series resistance.
What does Norton’s Theorem state?
Any linear circuit can be replaced with an equivalent circuit containing a single current source and a parallel resistance.
What is the Superposition Theorem?
In a linear circuit with multiple sources, the total response is the sum of the responses due to each source acting independently.
What does Joule’s Law describe?
The power (P) dissipated as heat in a conductor due to the current.
What is the formula for power in DC circuits?
P = VI.
What is the formula for power in AC circuits?
P = VIcosϕ.
How is energy (E) in a system calculated?
E = P x t.
What do capacitors and inductors store energy in?
Capacitors store energy in an electric field; inductors in a magnetic field.
What is the formula for impedance in AC circuits?
Z = √(R² + (XL - XC)²).
Fill in the blank: Capacitors store energy in a _______.
electric field.
Fill in the blank: Inductors store energy in a _______.
magnetic field.
True or False: Magnetic field lines start and end at specific points.
False.
What does Z represent in the impedance formula?
Impedance.
What does R represent in the impedance formula?
Resistance.
What do XL and XC represent in the impedance formula?
Inductive reactance and capacitive reactance, respectively.
