MYP Physics · 14 · structured
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Magnetism and electromagnetism · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- routine
- Marks
- 6
- Topics
- 2
- Answer
- Complete
An ideal transformer connects a 240 V alternating supply to a 12 V laboratory output. The primary coil has 800 turns. The output supplies 24 W to a device.
- a
Calculate Calculate the number of turns on the secondary coil.
3 marks - b
Calculate Calculate the output current.
2 marks - c
State State why a transformer requires a changing current rather than a steady direct current.
1 mark
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a
Calculate Calculate the number of turns on the secondary coil.
List the given quantities with units, identify the required quantity, write the governing relationship before substituting, and keep extra digits until the final line so rounding does not distort the result.
- 1
Uses Vs ÷ Vp = Ns ÷ Np.
- 2
Substitutes 12 ÷ 240 = Ns ÷ 800.
- 3
Obtains Ns = 40 turns.
b
Calculate Calculate the output current.
List the given quantities with units, identify the required quantity, write the governing relationship before substituting, and keep extra digits until the final line so rounding does not distort the result.
- 1
Uses P = VI and I = P ÷ V.
- 2
Obtains I = 24 W ÷ 12 V = 2.0 A.
c
State State why a transformer requires a changing current rather than a steady direct current.
Answer the command word directly and use precise physical vocabulary. Include only the distinct features or facts that earn marks, without burying them in unrelated background information.
- 1
A changing current produces changing magnetic flux and therefore an induced voltage in the secondary coil.
Private on this device