5. Jumper cables are used to start an automobile can get hot if usedfor more tha

Question

5.           Jumper cables are used to start an automobile can get hot if usedfor more than a few seconds. The jumper cables are 3 meters longwith a radius of 5 mm, and they are composed of copper. Copper hasa resistivity of 1.72 x 10 ^ -8 ohm – m at 20 degrees C,temperature coefficient of .0039 (1/C), and a density of 9000kg/m^3

a.           What is the total resistance of the pair of wires when thetemperature is 20C?

b.           How much does the resistance increase if the temperature becomes100C?

c.            What is the magnetic force magnitude and direction between thewires if the wire centers are separated by 20 mm and the current is40 amperes?

Thank you i will give top ratingasap! thanks again!

Explanation / Answer

   R = 2 L /A
  here is resistivity, L is length , Ais area = R2
   R = 2 L/ R2  
   = 2 ( 1.72x10-8)(3m)/ (5x10-3m)2   
   = 1.314x10-3 ohms
-------------------------------------------------------------------------------------------------------------- The increase in resistance of the two wiresis
   R ' = R [ 1 + (t2 - t1) ]
   =(1.314x10-3 ohms ) [ 1 + (0.0039)(100-20)]
   = 1.724x10-3 ohms
----------------------------------------------------------------------------------------------------------- The force between the wires is
   F = o I1I2 L / 2d
   =(4x10-7)(40)(40)(3) /2(20x10-3m)
   = 1.527x10-2N
   

Related Questions

Navigate

• Browse (All)
• Browse 5
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.