Systems Engineering: Electrical and Mechanical Theory

Vocabulary practice flashcards covering fundamental electrical engineering and mechanical systems principles, formulas, components, and safety standards.

Series Circuit

An electrical circuit where all components are connected one after another in a single continuous path or loop.

Parallel Circuit

An electrical circuit containing more than one branching loop, allowing current to flow simultaneously through separate paths.

Short Circuit

An abnormal electrical connection between two points of different potential that contains no load, causing excessive current flow.

Continuity

The presence of a complete and unbroken path for electric current flow, which occurs when a circuit is closed.

Mercury Switch

A switch consisting of a sealed glass tube containing two unconnected electrodes and liquid mercury that bridges the connection when tilted past a specific angle.

Reed Switch

A magnet-operated switch consisting of a pair of flexible, springy iron contacts encased inside a sealed glass tube that close when exposed to a magnetic field.

H-Bridge

An electronic circuit configuration of four switches that allows voltage to be applied in either direction across a DC motor to control its direction and braking.

Pulse Width Modulation (PWM)

A technique for controlling the average power delivered to a load by rapidly switching the voltage on and off in pulses.

Duty Cycle

The fraction or percentage of time during which an electrical pulse or signal is in the active or "ON" state over one complete cycle.

Voltage

The amount of potential energy per unit charge (or electrical "pressure") that pushes electrons through a circuit, measured in volts ($V$).

Current

The flow rate of electric charge or electrons through a conductor per second, measured in amperes ($A$).

Ohm's Law

The principle stating that the voltage drop across a conductor is directly proportional to the current flowing through it, represented by $V = I \times R$.

Electrical Power

The rate at which electrical energy is transferred or dissipated in an electrical circuit, calculated as $P = I \times V$ and measured in watts ($W$).

Kilowatt-Hour (kWh)

A unit of electrical energy representing the energy used by a $1\,kW$ appliance operating continuously for one hour ($1\,kWh = 1000\,Wh$).

Anode

The negative electrode of a battery from which electric charge flows into an external circuit when the battery is discharging.

Cathode

The positive electrode of a battery toward which electrons flow through the external circuit during discharging.

Battery Capacity

The measure of total electrical charge a battery can deliver over time, typically specified in ampere-hours ($Ah$) or milliampere-hours ($mAh$).

Photovoltaic Cell

A semiconductor device that absorbs sunlight and converts light energy directly into direct current ($DC$) electricity.

Root-Mean-Square Voltage ($V_{\text{RMS}}$)$$

The effective value of an alternating voltage that produces the same heating effect in a resistor as an equivalent direct current ($DC$) voltage, given by $V_{\text{RMS}} = \frac{V_{\text{peak}}}{\sqrt{2}}$.

Potentiometer

A three-terminal variable resistor configured to act as an adjustable voltage divider.

Rheostat

A variable resistor that uses only two terminals to adjust the resistance and control the flow of electric current.

Thermistor

A temperature-sensitive resistor made of metallic oxides whose electrical resistance varies significantly with temperature changes.

Light Dependent Resistor (LDR)

A variable photoresistor whose resistance decreases when light intensity increases.

Capacitor

An electrical component made of two conductors separated by an insulating dielectric, used to store energy in an electrostatic field.

Supercapacitor

A high-capacity capacitor capable of storing $10$ to $100$ times more energy per unit mass than conventional electrolytic capacitors, permitting rapid charge and discharge cycles.

Diode

A semiconductor device that allows electrical current to flow easily in one direction while blocking it in the reverse direction.

Flyback Diode

A protection diode connected in parallel and reverse-biased across an inductive load to suppress high reverse-voltage spikes when current is disconnected.

Full-Wave Bridge Rectifier

A circuit composed of four diodes arranged in a bridge configuration to convert alternating current ($AC$) into direct current ($DC$).

Zener Diode

A specialized diode that permits forward current flow like a standard diode, but also permits reverse current when the applied voltage exceeds its specific breakdown voltage.

Transistor

A three-terminal semiconductor device consisting of a base, collector, and emitter, used either as an electronic switch or as an amplifier.

Integrated Circuit (IC)

A microelectronic circuit containing thousands to billions of transistors, resistors, and capacitors fabricated directly onto a semiconductor wafer.

Microcontroller

A compact computer-on-a-chip containing a central processing unit (CPU), memory, and programmable input/output peripherals designed to control embedded systems.

Transducer

A device that converts variations in a physical quantity (such as pressure, temperature, or brightness) into an electrical signal, or vice versa.

Actuator

A mechanism or device that converts an input signal or energy into mechanical movement or force to operate a system.

Closed-Loop System

A control system that continuously monitors its output through feedback to adjust the process and achieve the desired state.

Electromechanical Solenoid

An electromechanical actuator consisting of a cylindrical wire coil wrapped around a movable iron or steel plunger that produces linear motion when energized.

Relay

An electrically operated electromagnetic switch that uses a small control current to open or close contacts on a separate, often higher-power circuit.

Transformer

An electrical device that uses electromagnetic induction between primary and secondary coils wound on an iron core to step up or step down alternating current ($AC$) voltages.

Commutator

A rotary electrical switch found on DC motors and dynamos that reverses current direction between the rotor windings and the external circuit.

Slip Rings

Continuous conductive metal rings used in AC motors and alternators to transfer electrical current between stationary brushes and rotating windings.

Dynamo

An electrical generator that uses a commutator to convert mechanical energy into direct current ($DC$) electricity.

Alternator

An electrical generator that uses slip rings to convert mechanical kinetic energy into alternating current ($AC$) electricity.

Linear Motion

Mechanical movement along a straight line in one direction.

Reciprocating Motion

Continuous, repetitive back-and-forth movement in a straight line.

Rotary Motion

Continuous movement in a circle around a central fixed axis.

Oscillating Motion

A repetitive, swinging back-and-forth motion along a curved path about a central pivot point.

Cam and Follower

A mechanical device comprising a profile-shaped rotating wheel (cam) and a contacting rod (follower) that converts rotary motion into reciprocating or irregular motion.

Camshaft

A rotating shaft incorporating multiple cam lobes designed to open and close engine valves with precise timing.

Crankshaft

A mechanical shaft featuring offset crankpins that converts the reciprocating linear motion of engine pistons into rotary motion.

Law of Conservation of Energy

The physical law stating that energy cannot be created or destroyed, only stored, transferred, or transformed from one form to another.

Mechanical Efficiency

The ratio of useful energy or work output to total energy or work input in a system, expressed as $\text{Efficiency} = \left(\frac{\text{Energy Out}}{\text{Energy In}}\right) \times 100\%$.

Bearing

A machine element designed to support moving parts, carry mechanical loads, and reduce frictional resistance between surfaces.

Mechanical Advantage (MA)

The factor by which a mechanism multiplies an applied effort force, calculated as $\text{MA} = \frac{\text{Load}}{\text{Effort}}$.

Velocity Ratio (VR)

The ratio of the distance moved by the effort force to the distance moved by the load force in a machine, given by $\text{VR} = \frac{\text{Distance moved by effort}}{\text{Distance moved by load}}$.

Inclined Plane

A simple machine consisting of a flat surface tilted at an angle, where the mechanical advantage equals the ramp length divided by the vertical height.

Torque

A turning effect or rotational force acting on an object about an axis, calculated as $\tau = \text{Force} \times \text{Radius}$ and measured in newton-meters ($N\,m$).

Torque Wrench

A specialized tightening tool calibrated to apply a specific, pre-determined torque setting to fasteners such as nuts and bolts.

Ball Joint

A spherical mechanical bearing consisting of a ball swivel inside a socket, allowing rotational movement in multiple directions.

Class 1 Lever

A lever where the fulcrum is located between the effort force and the load resistance.

Class 2 Lever

A lever where the load resistance is located between the fulcrum and the effort force.

Class 3 Lever

A lever where the effort force is applied between the fulcrum and the load resistance.

Bell Crank

A mechanical linkage pivoting on a fixed point that transmits motion and changes force direction through an angle, typically $90^{\circ}$.

Worm Gear

A gear mechanism comprising a screw-threaded cylindrical worm meshing with a spur gear to transmit motion through a right angle with high speed reduction.

Rack and Pinion

A mechanism composed of a round pinion gear meshing with a flat toothed rack that converts rotary motion into linear motion or vice versa.

Bevel Gear

Gears with conically shaped, angled teeth used in pairs to transmit rotary motion and torque between intersecting shafts at $90^{\circ}$.

Compound Gear Train

A gear system consisting of multiple pairs of gears where two intermediate gear wheels of different diameters are fixed to rotate together on the same shaft.

Ratchet and Pawl

A mechanism featuring a wheel with angled teeth (ratchet) and an engaging pivoted spring-loaded arm (pawl) that limits rotation to a single direction.

Moveable Pulley

A pulley that moves with the load being lifted, providing a mechanical advantage proportional to the number of supporting rope strands.

Pascal's Principle

The law of fluid mechanics stating that external pressure exerted on a confined fluid is transmitted equally and undiminished in all directions throughout the fluid.

Pneumatic System

A fluid power system that transmits and controls mechanical energy using compressed gas or air.

Hydraulic System

A fluid power system that transmits energy using pressurized, incompressible liquids (such as oil or water) to achieve high mechanical advantage.

Lockout Tag

A safety tag applied to an energy isolation device to prevent equipment operation during servicing, removable only by the authorized person who attached it.