The Transformer Quiz
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5 questions, one answer each
Each answer is checked as you go, with why.
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1. What must the current supplied to a transformer's primary coil be?
- A. Direct current
- B. Alternating current
- C. Zero current
- D. A constant current
2. In a step-up transformer, how do the number of turns on the coils compare?
- A. Secondary has more turns than primary
- B. Primary has more turns than secondary
- C. Both coils have equal turns
- D. There is no relationship between turns and voltage
3. A transformer has 200 turns on the primary coil and 20 turns on the secondary coil. If the primary voltage is 230 V, what is the secondary voltage?
- A. 2300 V
- B. 230 V
- C. 23 V
- D. 2.3 V
4. A 100% efficient transformer has a primary current of 2 A and a primary voltage of 230 V. If the secondary voltage is 23 V, what is the secondary current?
- A. 2 A
- B. 20 A
- C. 0.2 A
- D. 230 A
5. Why is electricity transmitted at high voltage rather than high current across the National Grid?
- A. High voltage makes electricity cheaper to generate
- B. High voltage reduces the current, which reduces power lost as heat since power loss depends on current squared
- C. High voltage is safer for wildlife near power lines
- D. High voltage allows the use of thinner iron cores in transformers