An ideal step down transformer is connected to main supply of 240V. It is desired to operate one 30W lamp of voltage 12V. What is the current in the primary coil?
Correct answer: A. 0.125 A
- A. 0.125 A
- B. 0.5 A
- C. 125 A
- D. 12.5 A
Explanation
Vp = 240 V, Vs = 12VPout = VsIs30W = 12V × IsIS = 2.5 AVs / Vp = Ip / Is VpIp = VsIs240 Ip = 12 × 2.5Ip = 30/ 240Ip = 0.125 AThis is numerical so it can only have one answer so option A is correct
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