Six identical miniature water pumps are connected in parallel to the 24 V secondary of a transformer. Each pump is rated at 24 V and 4.5 W.
The primary coil is connected to a 230 V supply. The transformer is 100% efficient.
The available maximum primary-current ratings are 0.10 A, 0.12 A, 0.15 A and 1.1 A.
What is the smallest maximum primary-current rating that allows all six pumps to operate at their rated power?
0.12 A0.12\ \mathrm{A}0.12 A
0.10 A0.10\ \mathrm{A}0.10 A
1.1 A1.1\ \mathrm{A}1.1 A
0.15 A0.15\ \mathrm{A}0.15 A
108 exam-style questions on Edexcel GCSE Physics 13.2 Transformers and the National Grid, covering 13.2.1 Transformers and induction, 13.2.2 The transformer turns-ratio equation, 13.2.3 The National Grid, 13.2.4 The transformer power equation, and 13.2.5 Advantages of high-voltage transmission. Each one has a worked solution and a mark scheme showing where the marks go.