HSC Physics Transformers
/Most HSC students can apply the transformer equation, but often the Physics principles are misunderstood. A tutorial sheet on transformers is given below.
- What is the role of a transformer in the transmission of electricity?
- Define one volt.
- Define the term emf.
- Is voltage is the same as emf?
- What is the role of the iron core in a transformer?
- What is meant by a soft iron core? Why is the soft iron core laminated?
- Can a transformer operate using DC? Sketch a graph showing the primary and secondary voltage (on different axes) when the DC voltage applied to the primary coil is switched on and then after a short time switched off.
- A common examination response is that "the induced emf in a coil equals the rate of change of the magnetic flux through the coil". Why is this incorrect?
- When AC enters the primary coil of a transformer in which coil is an emf induced? Primary, secondary or both?
- Assuming that the primary coil has low resistance, is the voltage applied to the primary coil equal to the counter emf induced in the primary coil? Is a counter emf induced in the secondary coil?
- Explain how an emf is induced in the secondary coil.
- The transformer equation uses the symbols Vp and Vs. Since transformers use AC, in which the current varies with time, what do these symbols represent?
