How Do You Calculate Transformer Efficiency with Given Power and Voltage?

Thread starter Nightwatchman
Start date May 3, 2009
Tags

Efficiency Transformer

AI Thread Summary

To calculate the efficiency of a transformer with 13W of primary power, the relevant equation is efficiency = (Psec / Pri) * 100. The primary voltage is given as 120V, while the secondary voltage is 12V and the number of turns in the secondary (Np) is 90. There is confusion regarding the number of primary turns (Np), as it is initially stated as unknown but later assigned a value of 90. Clarification is needed on whether Np is indeed 90 or if it remains unknown for the calculation. Accurate values for both primary and secondary turns are essential for determining the transformer's efficiency.

May 3, 2009

Nightwatchman

Homework Statement

What is the the efficiency of a transformer with 13w of primary power.
120Vp, Np unknow
12Vs, 90Np

Homework Equations

The Attempt at a Solution

eff= Psec/ Pri * 100

Physics news on Phys.org

May 4, 2009

rl.bhat

Homework Helper

120Vp, Np unknow
12Vs, 90Np
In first line you say Np is unknown and second line you say Np = 90. which is correct?

Thread 'Rolling without slipping on a curved surface'

Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .

View full post »

Thread 'I've come across another fluid pressure problem I don't understand'

Neglect gravity other than that of water; neglect friction. F1=ρgsh=1000*10*1*(1+4)=50000 N; F1=ρgsh=1000*10*0.1*4=4000 N; F3=50000-4000=46000 N?

View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...

View full post »