allstar question thread

[allstar]

someone please help!

[Thorium]

The Yallourn brown coal mine and power station is located in the Latrobe Valley, 150 km east of Melbourne.
One generator generates 500 megawatts of electric power at 10 kV. This is then transformed to 500 kV for
transmission to Melbourne. The total resistance of the transmission line used is 4ohms
calc the power loss?

P=VI
500x10^6=10x10^3 xI
I=500x10^2 A

I(s)/I(p)=V(p)/V(s)
I(s)/500x10^2=10x10^3/500x10^3
I(s)=1000 A

So, P(loss)=I^2R
                    =(1000)^2(4)
                    =4x10^6 ohm

[allstar]

thank you thorium!

Which of the following statements about a standing wave produced in a spring and the travelling wave that
produces the standing wave is incorrect?
A. The wavelength of the standing wave is equal to the wavelength of the travelling wave that
produced it.
B. The frequency of the standing wave is double the frequency of the travelling wave that produced it.
C. The distance between nodes on a standing wave is equal to half of the wavelength of the travelling
wave that produced it.
D. The amplitude of the antinodes on the standing wave is double the amplitude of the travelling wave
that produced it.