Recent content by Khuwwa

I solved the problem, thank-you for your help!

I got internal r = 2.76 Ohms, does that seem like a reasonable answer? I have to put it into emf = IR + Ir now. Is R (load resistance) just 220+100+470? And what about the two Is?

Thanks for the help!

5 volts = r * 0.00651 A + 220 * 0.01171 A + 100 * 0.00472 A + 470 * 0.00410 A

I tried as best I could to describe the circuit in my first paragraph: a DC power supply and three resistors, with varying currents along the circuit because it is only one closed loop of a larger circuit.

The problem: I have one loop of a larger circuit. It has a DC power supply set to 5 V, a 220 Ohm resistor, a junction, a 100 Ohm resistor, a junction, a 470 Ohm resistor, a junction, then it goes back to the power supply. The current through the 220 Ohm resistor is 11.71 mA (0.01171 A)...

This was one of those really small lab light bulbs, I don't know the wattage... Do you think I haven't made a mistake?

I'm supposed to make a graph of temperature vs. voltage. I actually have a number of voltages at which I'm supposed to calculate the temperature. Thank-you for helping, I was afraid my thread would be forgotten.

I think the temperature wouldn't rise that much from 20 degrees. 744 degrees is really hot, shouldn't it be more like 25 degrees or something?

R must be wrong, because all the other variables are correct, but the temperature can't be 744 degrees! I just want to know what value I should use for R.

Yes, this is nice. I am a student as well and I plan to continue in Biology.

I tried equation (2) again, this time paying more attention to the units. The answer comes out as 744 degrees Celsius, so it's not the wrong equation, but again, my R value. I found something in my notes saying Ro is correct, so it is R for sure. I need T in units of degrees Celsius.

Berkeman, a was given to me in the assignment, and that is how I am sure it is correct. I actually checked the units for equation (2), because I wasn't sure, and I got degrees Celsius... but I just tried again and I'm not sure! I'm going to try the calculation again, thank-you for pointing that...

Homework Statement The resistance of the tungsten filament in a light bulb changes with temperature according to equation (1), below. I am supposed to calculate the temperature of the light bulb at voltage 0.8280 volts and a current of 0.0853 amps. The bulb is connected to a 1.5915 volt...