Calculating the Efficiency of a Transformer for a Small Appliance

AI Thread Summary
To calculate the efficiency of the transformer for a small appliance with an input of 110 V and 6.4 W, and an output of 8.9 V at 270 mA, the formula used is efficiency = (power out / power in) * 100. The output power is calculated as 8.9 V multiplied by 0.270 A, resulting in approximately 2.403 W. The efficiency then becomes (2.403 W / 6.4 W) * 100, which equals about 37.5%. It is noted that while voltage drop theoretically shouldn't affect power output, real-world factors like heat generation lead to efficiency losses. Therefore, the final efficiency calculation reflects these practical considerations.
bleedblue1234
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Homework Statement



The specifications of a transformer for a small appliance read "Input: 110 V, 6.4 W" and "Output: 8.9 V, 270 mA". What is the efficiency of this transformer?

Homework Equations



P = I * V

V = I * R

The Attempt at a Solution



6.4 W / (8.9*(270*.001)) ---> I think this is wrong

I am just not sure how the voltage drop of the transformer would affect the power output...
 
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Your reasoning is absolutely correct, voltage drop theoretically shouldn't affect the power output, but in theory we assume that there is no losses, no heat generated etc.
Thus when such a question pops up (power out)*100/(power in ) will give you the efficiency.
 

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