Basic Electrical Flashcards
7 cards from real BEE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Basic Electrical flashcards as text
A 60 W lamp operates at 120 V. What is its resistance?
Answer: 240 Ω
R = V²/P = (120)²/60 = 14400/60 = 240 Ω.
In a star (Y) connected three-phase system, the relationship between line voltage (V_L) and phase voltage (V_ph) is:
Answer: V_L = √3 × V_ph
In a balanced Y connection, the line voltage is √3 times the phase voltage.
Which instrument is used to measure electrical energy consumption?
Answer: Energy meter (kWh meter)
An energy meter (kilowatt-hour meter) integrates power over time to measure total energy consumed.
The skin effect in conductors causes current to:
Answer: Concentrate near the surface at high frequencies
At high frequencies, AC current tends to flow near the conductor's outer surface, reducing the effective cross-sectional area.
What is the reactive power in a circuit where V = 100 V, I = 5 A, and the power factor angle θ = 30°?
Answer: 250 VAR
Q = V·I·sin θ = 100 × 5 × sin 30° = 500 × 0.5 = 250 VAR.
A transformer has 200 primary turns and 50 secondary turns. If the primary voltage is 240 V, what is the secondary voltage?
Answer: 60 V
V2/V1 = N2/N1 → V2 = 240 × (50/200) = 60 V.
Which of the following correctly defines 'electric potential difference'?
Answer: Work done per unit charge to move charge between two points
Potential difference (voltage) is defined as the work done per unit positive charge moved between two points.