Previous DC Generator theory Next Battery Theory Quiz Test-1

NEC CODE NEC 2023

Transformer Practice Quiz Test-1

Free Online Quiz test transformer theory and practice.

How this test works

Read each question carefully

Look for absolute words like always / never — they often distinguish the right answer.

Manage your time

You have 15 min for 10 questions. Skip tough ones and come back.

Progress is auto-saved

Your answers are saved locally — a page refresh won't lose your work.

Review your answers

After submitting you'll see every explanation and your NEC references.

Frequently Asked Questions

Yes — free, no signup required. Each question links to the relevant NEC article so you can study the code directly.

The National Electrical Code (NFPA 70) is the benchmark standard for safe electrical installation in the US. It is updated every 3 years by the NFPA.

Study the edition adopted by your state. As of 2025, most states use the 2020 or 2023 NEC. These tests are written to the 2023 edition.

The most tested articles are 100 (Definitions), 200–250 (Wiring & Grounding), 300–314 (Wiring Methods), 400–411 (Conductors), 430 (Motors), and 700–701 (Emergency Systems).

10

Questions

15 min

Time

70%

Pass

Timer starts immediately. Progress is auto-saved.

Transformer Practice Quiz Test-1 — Question List

Question 1: What happens when a DC supply is supplied to Primary of a transformer?

A small current flows in primary
Core losses will increase
Leakage reactance is increased
Primary winding may burn out

Question 2: <span style="color: #000000;">A transformer has an efficiency of 90% which works at 120 V, 3.6 kW. If the secondary voltage is 240 Volts, what is the primary current? </span>

40 amperes
20 amperes
30 amperes
50 amperes

Question 3: A transformer having 1500 turns in primary winding 300 turns in secondary winding is supplied with 120 volts AC. What is its secondary Voltage?

24 Volts
48 Volts
12 Volts
60 Volts

Question 4: A three-phase 4 wire electrical system phase-phase voltage is 480 volts. what is its phase to neutral voltage?

377 volts
277 volts
480 volts
240 volts

Question 5: The Scott connection is used to change three phase power into two phase power.

True
False

Question 6: What is the phase angle between primary and secondary of a transformer?

180 degrees
90 degrees
270 degrees
360 degrees

Question 7: The ampere current in primary side of a transformer is directly proportional to ampere current in secondary.

True
False

Question 8: What is the best way to connect to single phase transformers to act as three phase transformer?

open-delta
Scott connection
deltas-star
none

Question 9: Transformer is laminated to reduce .....................

eddy current losses
hysteresis losses
both eddy current and hysteresis losses
None

Question 10: The Transformer is not used in DC Power supply system because

high losses will occur
There is no need of step up of dc power supply
the rate of change of flux is zero

EXAM CARD NEC CODE

Questions10

Time limit15 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Timer starts immediately. Progress is auto-saved.