The resistivity of gold is 2.44 times 10-8 Ohm m at a temperature of 20 degree C

Question

The resistivity of gold is 2.44 times 10-8 Ohm m at a temperature of 20 degree C. A gold wire, 0.6 mm in diameter and 44 cm long, carries a current of 480 mA. What is the number of electrons per second passing a given cross section of the wire? When a voltage difference is applied to a piece of copper wire, a 10.0 mA current flows. If the copper wire is replaced with a silver wire with twice the diameter of the copper wire, how much current will low through the silver wire? The lengths of both wires are the same, and the voltage difference remain unchanged. (The resistivity of copper is 1.68 times 10-8 Ohm m, resistivity of silver is 1.59 times 10-8 Ohm m.)

Explanation / Answer

1) we know, 1 e = 1.6*10^-19 C

1 C = 1/(1.6*10^-19) e

= 6.25*10^18 e

I = 480 mA

= 480*10^-3 C/s

= 0.48 C/s

= 0.48*6.25*10^18 e/s

= 3*10^18 e/s <<<<<<<---------Answer

2) potenatil diffrence across both wires is same

so, V_copper = V_silver

I_copper*R_copper = I_silver*R_silver

I_copper*rho_copper*L/A_copper = I_silver*rho_silver*L/A_silver

I_copper*rho_copper/A_copper = I_silver*rho_silver*/(4*A_copper)

I_copper*rho_copper = I_silver*rho_silver/4

I_silver = 4*I_copper*rho_copper/rho_silver

= 4*10*10^-3*1.68/1.59

= 42.3*10^-3 A or 42.3 mA <<<<<<<---------Answer

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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