Recent content by Kobayashi

Oh yes, 3.96 x 10^15. Is this the correct final answer. Thanks again for all your help.

Hi, thanks for your help. The only alternative I can think of is the Joules per second divided by the Joules per photon. This gives 3.96 x 10^16 Photons per sec. Is this correct?

Okay so I get: 0.0009 Joules/second and (1.42 eV) * 1.602 x10^-19 = 2.27 x 10^-19 Joules - Is this correct? Is this the energy per photon? Does (energy/photon)/(energy/second) not give photons/second. Is that how the problem is solved?

Where is the bandgap taken into account?

Hi, I have a question asking me to find the number of photons emmitted per second. I am given the information that the Gallium Arsenide diode laser emit 0.9 mW of power inside a CD player. The bandgap of the Gallium Arsenide is 1.42 eV. What equation is used to find this?

Homework Statement Can someone please explain to me how to find the voltage across BD in the attached circuit. I can't do these examples. Please help. Homework Equations The Attempt at a Solution When I shorted one source I get the source current as 10.08mA and a voltage drop...

Thanks, that helps me a lot. I've learned matrices before but I've completely forgotten. Thanks for reminding me.

Thanks. I now have a question about analysis of a circuit containing three meshes. When you get an equation e.g: -11.3I1 + 9.1I2 +0I3 = 18 9.1I1 -23.4I2 + 6.8I3 = -18 0I1 + 6.8I2 -10.1I3 = -3 How do you find the individual currents in this case. I read you can use Gaussian...

Here it is: https://www.physicsforums.com/attachment.php?attachmentid=11872&d=1196884527

I tried uploading it again.

I also use firefox and it works for me. Have you tried internet explorer?

Homework Statement Use mesh analysis to find the current through the 4 Ohm resistor. Homework Equations The Attempt at a Solution From this circuit I managed to work out the three mesh equations using mesh analysis. Mesh 1 = 7I1 + 4I2 = 67 Mesh 2 = -4I1 + 15I2 - 6I3 = 152...

Thanks, I now managed to get the correct answer.

So, R^2 + 2Rr + r^2 + 90 - (V^2*R) Becomes, R^2 + 10R + 115 - 10000R =0 R^2 + 9990R + 115 = 0 From this I still can't get the correct answer when using the quadratic formula. Is it the load voltage or the supply voltage you use in this case? The two answers should be 100.75 Ohms and 0.25...

[SOLVED] Calculate Load Resistance Homework Statement Find RL if PL is 90W. Homework Equations PL= ((V^2)*(RL))/((RL+r)^2) The Attempt at a Solution I calculated the internal resistance to be 5 Ohms on my circuit with a supply voltage of 100V So, 90W = ((100^2) * (RL))/((RL +...