ATAR Notes: Forum
HSC Stuff => HSC Science Stuff => HSC Subjects + Help => HSC Physics => Topic started by: bloop on July 20, 2017, 08:57:45 pm
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Hi, I need help with the below question, thank you :D
An 85% efficient transformer is shown below (image is too big)
Primary coil = 90 turns.
Secondary coil = 300 turns.
If a current of 2mA flows in the secondary coil and power output is 100W, the primary voltage is what?
Answer is 17638 V
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Hi, I need help with the below question, thank you :D
An 85% efficient transformer is shown below (image is too big)
Primary coil = 90 turns.
Secondary coil = 300 turns.
If a current of 2mA flows in the secondary coil and power output is 100W, the primary voltage is what?
Answer is 17638 V
P = VI
100 = 2x10^-3 x V
Vs = 50,000
Vp/Vs = np/ns
Vp = 50000*90/300
Vp = 15,000 but it's 85% efficiency
So Vp = 15,000/0.85
Vp = 17,647 V