THE TRANSFORMER
3 marks · NormalA student investigates transformers using different numbers of turns on the secondary coil, measuring output voltages. Her results:
| Turns on Secondary Coil | Output Voltage (V) |
|---|---|
| 100 | 4.0 |
| 200 | 8.1 |
| 300 | 12.0 |
| 400 | 15.8 |
Describe the relationship between the number of turns on the secondary coil and the output voltage.
Estimate the output voltage if the secondary coil had 500 turns.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) The output voltage increases as the number of turns increases; directly proportional relationship. · must show increases, proportional
(b) ≈19.8 V · must show estimate by proportion
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States voltage increases as turns increase and/or describes relationship as (directly) proportional.
M1 (b) · 1 mark · Applies proportional relationship or uses data trend to estimate voltage for 500 turns.
A1 (b) · 1 mark · Estimates output voltage as 19.8 V (accept answers in range 19–20 V). (follow-through)
Worked solution
a) The output voltage increases as the number of secondary turns increases. The relationship is directly proportional.
b) Using the proportionality: 400 turns → 15.8 V, so 500 turns =