{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# oldhw12 - oldhomewk 12 LEE BENJAMIN Due 4:00 am Question 1...

This preview shows pages 1–2. Sign up to view the full content.

oldhomewk 12 – LEE, BENJAMIN – Due: Sep 30 2007, 4:00 am 1 Question 1, chap -1, sect -1. part 1 of 1 10 points Why are thick wires rather than thin wires usually used to carry large current? 1. Thick wires are difficult to break. 2. Thick wires have a larger heat capacity. 3. Thick wires are easier to make. 4. Thick wires have less resistance. correct Explanation: Thick wires have less resistance and will more effectively carry currents without exces- sive heating. Question 2, chap 27, sect 2. part 1 of 1 10 points A resistor is made from a hollow cylinder of length l , inner radius a , and outer radius b . The region a < r < b is filled with material of resistivity ρ . Current runs along the axis of the cylinder. The resistance R of this component is 1. R = ρ ℓ b 2 π a 4 2. R = ρ ℓ π b 2 3. R = ρ ℓ π a 2 4. R = π b 2 ρ 5. R = ρ ℓ π ( b 2 - a 2 ) correct 6. R = ρ a πℓ b 2 7. R = ρ ℓ a 2 π b 4 8. R = 2 πρ ℓ ( b 2 - a 2 ) 9. R = 2 ρ ℓ π b 2 10. R = π ( b 2 - a 2 ) ρ Explanation: By definition R = ρ A = ρ π b 2 - π a 2 = ρ ℓ π ( b 2 - a 2 ) . Question 3, chap 27, sect 3. part 1 of 1 10 points Which of the following will cause the elec- tric resistance of certain materials known as superconductors to suddenly decrease to es- sentially zero?

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 3

oldhw12 - oldhomewk 12 LEE BENJAMIN Due 4:00 am Question 1...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online