Electrical Quantities & Ohm's Law - Vocabulary Flashcards

Vocabulary flashcards covering key electrical quantities, basic circuit concepts, and unit terminology from the lecture notes.

Coulomb's Law

The electrostatic force between two point charges is proportional to the product of the charges and inversely proportional to the square of the distance between them.

Coulomb (C)

The SI unit of electric charge; one coulomb equals 6.25 × 10^18 electrons.

Conventional Current

Flow of positive charge from the positive to the negative terminal.

Electron Current Flow

Flow of electrons from the negative to the positive terminal.

Direct Current (DC)

Electrical current that flows in one direction only.

Alternating Current (AC)

Electrical current that periodically reverses direction.

Ampere (A)

Unit of electric current; one ampere equals one coulomb per second.

Ammeter

Instrument used to measure current in amperes.

Ohm (Ω)

Unit of resistance; the resistance between two points where a constant 1 V creates 1 A.

Resistance

Opposition to the flow of electric current; measured in ohms (Ω).

Voltage (Volts, V)

Electrical pressure; the potential difference that drives current.

Voltmeter

Instrument used to measure voltage.

EMF (Electromotive Force, E)

The voltage provided by a source; symbol E or V.

Current (I)

Rate of flow of electric charge; measured in amperes.

Power (P)

Rate at which electrical energy is transformed or transferred.

Watt (W)

Unit of electrical power; one watt equals one joule per second.

Kilowatt (kW)

Unit equal to 1,000 watts.

Horsepower (hp)

Unit of power; 1 hp = 746 W (also equals 550 ft-lb/s).

1 hp in watts

1 hp equals 746 watts.

1 hp in ft-lb/s

1 hp equals 550 foot-pounds per second.

1 hp in ft-lb/min

1 hp equals 33,000 foot-pounds per minute.

BTU (British Thermal Unit)

Amount of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit.

Calorie (cal)

Amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius.

1 BTU/hr to Wh

1 BTU per hour is approximately 0.293 watt-hours.

1 Cal/s to Watts

1 Calorie per second is approximately 4.19 watts.

Joule (J)

Unit of energy; 1 joule equals 1 newton meter.

Watt-second (J)

Unit of energy equal to one joule.

1 BTU

Approximately 1055 joules.

Work (ft-lb)

Mechanical work measured in foot-pounds (force times distance).

1 Watt-second equals 1 Joule

Equality between the energy units watt-second and joule.

Ohm's Law

In DC circuits, current is directly proportional to voltage and inversely proportional to resistance; V = I R, I = V/R, R = V/I.

Voltage (V) symbol

Voltage is represented by E or V in equations.

Current (I) symbol

Current is represented by I or A in equations.

Resistance (R) symbol

Resistance is represented by R in ohm's law.

P equals VI

Power equals voltage times current.

P equals I^2R

Power due to resistance and current equals I squared times R.

P equals E^2/R

Power related to EMF and resistance equals E squared divided by R.

EMF symbol (E)

Voltage supplied by a source; the EMF is represented by E.

Metric Prefix Kilo (k)

Multiplier of 10^3.

Metric Prefix Mega (M)

Multiplier of 10^6.

Metric Prefix Giga (G)

Multiplier of 10^9.

Metric Prefix Tera (T)

Multiplier of 10^12.

Metric Prefix Milli (m)

Multiplier of 10^-3.

Metric Prefix Micro (µ)

Multiplier of 10^-6.

Metric Prefix Nano (n)

Multiplier of 10^-9.

Metric Prefix Pico (p)

Multiplier of 10^-12.

Engineering notation

Engineering notation uses powers of 1000 rather than powers of 10.

SI system

System International of Units; worldwide standard for measurements.

Hertz (Hz)

Unit of frequency; 1 per second.

Farad (F)

Unit of capacitance; C/V.

Lumen (lm)

Unit of luminous flux; lm.

Lux (lx)

Unit of illuminance; lm/m^2.