The Table shows information about three transformers, P, Q and R.
Table
| Transformer | Number of turns in primary coil | Number of turns in secondary coil | Potential difference across primary coil in V\text{V}V | Potential difference across secondary coil in V\text{V}V |
|---|---|---|---|---|
| P | 500 | 50 | 230 | ? |
| Q | ? | 1200 | 12 | 48 |
| R | 2000 | 100 | 230 | 11.5 |
Use the equation: potential difference across primary coilpotential difference across secondary coil=number of turns in primary coilnumber of turns in secondary coil\dfrac{\text{potential difference across primary coil}}{\text{potential difference across secondary coil}} = \dfrac{\text{number of turns in primary coil}}{\text{number of turns in secondary coil}}potential difference across secondary coilpotential difference across primary coil=number of turns in secondary coilnumber of turns in primary coil
Calculate the potential difference across the secondary coil of transformer P.
Calculate the number of turns in the primary coil of transformer Q.
Identify which of the transformers are step-down transformers.
Give a reason for your answer.
48 exam-style questions on OCR GCSE Physics 4.2 Uses of magnetism, covering 4.2.1 The motor effect, 4.2.2 Fleming's left-hand rule, 4.2.3 The force on a current-carrying conductor, 4.2.4 The electric motor, 4.2.5 Electromagnetic induction, 4.2.6 Alternators and dynamos, 4.2.7 How transformers work, 4.2.8 Transformer turns ratio, 4.2.9 Potential differences and turns in transformers, and 4.2.10 Microphones, loudspeakers and headphones. Each one has a worked solution and a mark scheme showing where the marks go.