Electricity Transmission & Distribution Quiz
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5 questions, one answer each
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1. Why is electricity transmitted across the National Grid at high voltage?
- A. To increase current and speed up transmission
- B. To reduce current and minimise heating losses in cables
- C. To make the cables lighter
- D. To allow direct current to be used
2. What material is the core of a transformer typically made from?
- A. Copper
- B. Soft iron
- C. Aluminium
- D. Plastic
3. A transformer has 200 turns on the primary coil and 2000 on the secondary. If the primary pd is 230 V, what is the secondary pd?
- A. 23 V
- B. 230 V
- C. 2300 V
- D. 46000 V
4. Why do transformers not work with direct current (dc)?
- A. DC produces too much heat
- B. DC does not create a changing magnetic field, so no pd is induced in the secondary coil
- C. DC voltage is always too low
- D. Transformers can only handle high frequencies
5. An ideal transformer has a primary current of 4 A at 230 V. If the secondary pd is 2300 V, what is the secondary current?
- A. 0.4 A
- B. 4 A
- C. 40 A
- D. 0.04 A