Electrical Engineering and AC Circuit Principles

Alternating Current and RMS Values

• RMS value means: Peak value divided by 1.41.
• The effective RMS is: Smaller than the peak value.
• An effective RMS value circuit of 10: Results in 14.14.
• Measuring voltage with AC voltmeters: Displays the effective value.
• The AC curve can be present: It decreases from 1 to 0.
• Instant value of AC power: The value at a specific time of the cycle.

AC Motors and Alternators

• Single phase alternator: Stator windings connect in series.
• Types of AC motors: Synchronous and induction motors.
• AC motors speed is relative to: The number of poles and frequency.
• Shaded poles: These facilitate starting.
• Three-phase synchro has: 3 stator and 1 rotor windings.

Circuit Components and Filters

• Electronic circuit designed as a Band pass filter: Filters specific frequencies.
• Single electronic Low pass filter: Allows low frequencies to pass.
• Electronic circuit which acts as a High pass filter: Allows high frequencies to pass.
• Thermistor: A type of automatic variable resistor where resistance decreases as temperature increases (negative temperature coefficient).
• Photo conductive cell: Responds to light intensity.
• Color indicates: The resistance value of the resistor.

Transformers and Protection Devices

• In an autotransformer: The primary and secondary coils share windings.
• Current transformer: Used for circuit protection and control devices.
• Transformers: These change levels to different voltages.
• Circuit breakers use: DC power.
• How many turns does the secondary of a step-up transformer have? More than 1.
• Primary winding of a transformer: Has 100 turns while the secondary has 400.

Atomic Theory and Electrical Charge

• Ions are atoms: Characterized by a lack or excess of electrons.
• Positive ions are: Atoms with a high number of protons.
• Atoms are normally electrically: Neutral.
• Electrons are: Electrically negative charged particles.
• Electrons in motion: Constitute an electrical current.
• Electrical charge is measured in: Coulombs.
• Electrical current is expressed as: Charge produced over time.
• Electrical current is measured in: Amperes.
• What material is a good conductor? Material with free electrons.

Passive Component Calculations

• Equivalent of parallel connected resistors: 1/Rn... (division).
• Equivalent of resistors in series: Rn = R1 + R2 + R3 (summation).
• In a circuit with 2 resistors: 1/Rt = 1/R1 + 1/R2.
• Capacitors in series: 1/Ct = 1/C1 + 1/C2 + 1/C3.
• Capacitors in parallel: Ct = C1 + C2 + C3.
• When 2 capacitors are in parallel: The sum total is Ct = C1 + C2.
• Inductors in series: Lt = L1 + L2 + L3.
• Inductors in parallel: Calculated as 1 divided by (1/L1 + 1/L2 + 1/L3).

Advanced Circuit Principles

• What is the key? Electromagnetic induction.
• The capacity reactance in an AC circuit: Acts opposite.
• Frequency: The number of cycles in a period.
• Term frequency alternating: Number of cycles per unit of time/second.
• Period on a cycle AC: f = 2t.
• Power: Defined as the rate of consumed energy in a period.
• In DC purpose commutator: Provides electrical contact.
• The basic to create AC power: Electrical current is created.
• Impedance triangle consists of: Reactance, resistance, and impedance.
• Left-hand rule: Relates to magnetic flux.
• How much impedance for 3-ohm resistance and 4-ohm reactance? 5 ohms.
• What is the name of the frequency? Resonant frequency.
• What is the power in delta 115 x 5? 575W.
• Most conductors' resistance increases: As temperature increases.
• What is retentivity? The ability of a material to hold magnetism.
• Kirchhoff's Current Law says: The sum of voltages.