Figure ( a ) shows a rod of resistive material. The resistance per unit length o

Question

Figure (a) shows a rod of resistive material. The resistance per unit length of the rod increases in the positive direction of thexaxis. At any positionxalong the rod, the resistancedRof a narrow (differential) section of widthdxis given bydR= 5.05x dx, wheredRis in ohms andxis in meters. Figure (b) shows such a narrow section. You are to slice off a length of the rod betweenx= 0 and some positionx=Land then connect that length to a battery with potential differenceV= 7.9 V (Figure (c) below). You want the current in the length to transfer energy to thermal energy at the rate of 215 W. At what positionx=Lshould you cut the rod?

Explanation / Answer

Given that resistance r =5ohms VoltageV = 5 volts
PowerP = 200 watts
As we know that Power P = Voltage V * Current I Thecurrent (I)flowing through the rod will be
I= 200 watts/ 5 volts
= 40amps
Theresistance (R)of the rod will be
R = V / I
= 5 volts / 40 amps
=0.125 ohms
The resistance of 1meter rod is 5ohms
for0.125 ohms ofresitance the rod length must be 2.5 cm



change values do some alebra may be it helpful

Related Questions

Navigate

• Browse (All)
• Browse F
• Subjects

---

---

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