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Re: Detector Building C

Posted: December 5th, 2020, 6:48 pm
by ThomasL
Yay! Here's the next one:

You have a tungsten wire with length of 1.20 m and diameter 1.50 mm.
1. What is its resistance? (20.0 degrees C)
2. If temperature is increased to 25.5 degrees C, what is the new resistance?
3. Briefly explain the cause of the change in resistance.

Re: Detector Building C

Posted: January 30th, 2021, 7:17 pm
by ThomasL
1. What is the energy of an LED bandgap, in eV, if the photon wavelength emitted is 550 nm? What is this value in Joules?
2. What is a thermocouple composed of?
3. Describe the difference between accuracy and precision.

(Oops! Forgot I already sent one... But here's another one for your practicing pleasure, I guess :))

Re: Detector Building C

Posted: February 4th, 2021, 1:01 pm
by Tailsfan101
ThomasL wrote:
December 5th, 2020, 6:48 pm
Yay! Here's the next one:

You have a tungsten wire with length of 1.20 m and diameter 1.50 mm.
1. What is its resistance? (20.0 degrees C)
2. If temperature is increased to 25.5 degrees C, what is the new resistance?
3. Briefly explain the cause of the change in resistance.
1. 3.8 x 10^-8 Ohms
2. 3.9 x 10^-8 Ohms
3. Resistance and temperature are proportional
ThomasL wrote:
January 30th, 2021, 7:17 pm
1. What is the energy of an LED bandgap, in eV, if the photon wavelength emitted is 550 nm? What is this value in Joules?
2. What is a thermocouple composed of?
3. Describe the difference between accuracy and precision.

(Oops! Forgot I already sent one... But here's another one for your practicing pleasure, I guess :))
1. 2.2 eV, 3.5 x 10^-19 J
2. Two electrical conductors forming an electrical junction
3. Accuracy refers to how close a number is to the actual answer, whereas precision refers to how many figures the answer goes to. For example, if the real answer is 2.55, 9.6044 is more precise, but 3 is more accurate.

Re: Detector Building C

Posted: February 9th, 2021, 5:44 pm
by ThomasL
Tailsfan101 wrote:
February 4th, 2021, 1:01 pm
ThomasL wrote:
December 5th, 2020, 6:48 pm
Yay! Here's the next one:

You have a tungsten wire with length of 1.20 m and diameter 1.50 mm.
1. What is its resistance? (20.0 degrees C)
2. If temperature is increased to 25.5 degrees C, what is the new resistance?
3. Briefly explain the cause of the change in resistance.
1. 3.8 x 10^-8 Ohms
2. 3.9 x 10^-8 Ohms
3. Resistance and temperature are proportional
ThomasL wrote:
January 30th, 2021, 7:17 pm
1. What is the energy of an LED bandgap, in eV, if the photon wavelength emitted is 550 nm? What is this value in Joules?
2. What is a thermocouple composed of?
3. Describe the difference between accuracy and precision.

(Oops! Forgot I already sent one... But here's another one for your practicing pleasure, I guess :))
1. 2.2 eV, 3.5 x 10^-19 J
2. Two electrical conductors forming an electrical junction
3. Accuracy refers to how close a number is to the actual answer, whereas precision refers to how many figures the answer goes to. For example, if the real answer is 2.55, 9.6044 is more precise, but 3 is more accurate.
Yay! Let's see:
1. Value is the same, but my answer is offset by a magnitude of 10^-6 -- I think you forgot the 10^-3 part of 1.50 mm.
2. Same again, but again, offset in terms of magnitude.
3. Was looking for something in terms of a molecular-level explanation -- that is, the increased temperature causes electron motions within the metal to become much more chaotic, leading to more frequent collisions that impede net motion in the direction of the applied potential.
For 1 and 2, I was also looking for something with 3 sigfigs.

Other set of answers look perfect:) Your turn!

Re: Detector Building C

Posted: February 10th, 2021, 11:03 am
by Tailsfan101
1. A resistor has a resistance of 346 Ohms. What colors in the resistance color code does this correspond to (ignoring the tolerance band)?
2. Which contains more electrons compared to holes, an N-type or P-type semiconductor?
3. What is the difference between NTC and PTC thermistors?