A high-frequency power supply unit for a marine sonar transponder contains a transformer designed to increase the voltage from the main input to the transducer unit.
(i) Name the type of transformer that increases voltage.
(ii) Explain why the transformer core is made of a soft magnetic material, such as iron.
(i) State the equation linking primary voltage, secondary voltage, and the turns ratio.
(ii) The transformer inside the power supply has 320 primary turns and 8000 secondary turns. The input voltage to the primary coil is 110 V. Calculate the output voltage on the secondary coil.
(i) The alternating current used in the power supply has a switching frequency of 95,000 Hz. The unit vibrates at this same frequency. Explain why these vibrations cannot be heard by a human.
(ii) A diagnostic LED on the unit flashes regularly to indicate normal status. There is a flash every 1.25 ms. Calculate the frequency of these flashes.
20 exam-style questions on Edexcel IGCSE Physics Electromagnetic induction. Each one has a worked solution and a mark scheme showing where the marks go.