Three charges Q_1, Q_2, and Q_3 are aranged along the x-axis and separated as sh

Question

Three charges Q_1, Q_2, and Q_3 are aranged along the x-axis and separated as shown in the diagram below. Q_1 = 5 muC, Q_2 = -5 muC and Q_3 = 7 muC. Calculate the Potential at P 3) A conductor is 10,000 m long and has a cross sectional area of 0.5 cm^2 Calculate the resistance of the wire when it is heated to 300 degreeC given that the wire is initially at room temperaure of 20 degreeC and its coefficient of resistance is rho_0 = 1.72 times 10^-8 Ohm.m The temperature coefficient of resistance alpha = 3.9 times 10^-3/C at room temperature.

Explanation / Answer

(2)
Electric Potential at Point P is given by,
Vp = k*q1/r1 + k*q2/r2 + k*q3/r3
Vp = 8.9* 10^9 * 10^-6 [ 5/((4+6+4)/100) -  5/((6+4)/100) +  7/((4)/100) ]
Vp = 1.45 * 10^6 V

Correct Option :- C

(3)
L = 10000 m
A = 0.5 * 10^-4 m^2
= 1.72 * 10^-8 m
= 3.9 * 10^-3 /C

Resistance at temperature at 20o C,
R = *L/A
R = 1.72 * 10^-8 * (10000)/( 0.5 * 10^-4)
R = 3.44

Now Resistance at temperature at 400o C,

R = Ro * [1 + *(T - To) ]
R = 3.44 * [1 + 3.9 * 10^-3 * (400 - 20) ]
R = 8.5
Correct Option :- A

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

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