Journeyman Electrician’s Exam Journeyman Electrician's Basic Formula 3

Question 1

Two resistors of 12Ω and 6Ω are connected in parallel. What is the equivalent resistance?

Accepted Answer

4 Ω

Answer

1/R = 1/12 + 1/6 = 1/12 + 2/12 = 3/12; R = 4 Ω.

Question 2

A single-phase transformer has a primary voltage of 480V and a turns ratio of 4:1. What is the secondary voltage?

Accepted Answer

120 V

Answer

V_secondary = V_primary / turns ratio = 480 / 4 = 120 V.

Question 3

What formula is used to calculate electrical energy consumed over time?

Accepted Answer

E = P × T

Answer

Energy (in watt-hours) = Power (watts) × Time (hours).

Question 4

A 10 kW load operates for 8 hours. How many kilowatt-hours (kWh) does it consume?

Accepted Answer

80 kWh

Answer

Energy = 10 kW × 8 h = 80 kWh.

Question 5

In a three-phase system, apparent power (VA) is calculated as:

Accepted Answer

VA = √3 × V_L × I_L

Answer

Three-phase apparent power = √3 × line voltage × line current.

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