| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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(Physics only) Students should be able to apply the equation linking the pds and number of turns in the two coils of a transformer to the currents and the power transfer involved, and relate these to the advantages of power transmission at high potential differences. |
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(Physics only) How does the equation linking the pds and number of turns in the two coils of a transformer link to the to the currents and the power transfer involved. Relate these to the advantages of power transmission at high potential difference. Explain how a step-up transformer will increase the potential difference in the secondary coil compared to the primary coil but it will also decrease the current. This happens as the electrical power on both primary and secondary coils remains the same.
GF: Research why American electricity companies switched from using d.c. to a.c. What are the advantages of sending electricity at high potential differences? |
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(Physics only) A basic transformer consists of a primary coil and a secondary coil wound on an iron core. |
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(Physics only) What is the basic structure of a transformer? Demo:
Making a transformer
Institute of Physics: Episode 416 – Generators and transformers |
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(Physics only) Iron is used [for a core] as it is easily magnetised. Knowledge of laminations and eddy currents in the core is not required. |
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(Physics only) Which metal is used for the core in transformers? |
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(Physics only) The ratio of the potential differences across the primary and secondary coils of a transformer Vp and Vs depends on the ratio of the number of turns on each coil, np and ns .
EQUATION |
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(Physics only) The ratio of the potential differences across the primary and secondary coils of a transformer (Vp and Vs) depends upon the ratio of what? |
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(Physics only) In a step-up transformer Vs > Vp |
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(Physics only) In a step-up transformer which has the greatest potential difference, primary (Vp) or secondary (Vs) coils? |
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(Physics only) In a step-down transformer Vs < Vp |
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(Physics only) In a step-down transformer which has the greatest potential difference, primary (Vp) or secondary (Vs) coils? |
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(Physics only) If transformers were 100 % efficient, the electrical power output would equal the electrical power input. |
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(Physics only) What would the relationship be between total power input and output in a transformer if it were 100% efficient? |
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(Physics only) Vs ? Is = Vp ? Ip
Where
Vs ? Is is the power output (secondary coil) and
Vp ? Ip is the power input (primary coil).
power input and output, in watts, W |
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(Physics only) Vp x Ip = the ______ _______ (primary coil).
power input
Vs x Is = the _______ ______ (secondary coil)power output |
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(Physics only) Students should be able to explain how the effect of an alternating current in one coil in inducing a current in another is used in transformers |
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(Physics only)Explain how the effect of an alternating current induces a current in another transformer. |
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(Physics only) Students should be able to explain how the ratio of the potential differences across the two coils depends on the ratio of the number of turns on each |
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(Physics only) How does the ratio of the potential differences across the two coils depends on the ratio of the number of turns on each? |
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