Only full detailed answer will be rated Compared to a 30.0 Ohm resistor another

Question

Only full detailed answer will be rated

Compared to a 30.0 Ohm resistor another resistor made from the same material has twice (2 00X) the cross sectional area, but half (0 500x) the length. If this second resistor is connected in a series with a 12.0 V battery, what is the current in this circuit? (20.4) In a circuit, a 24.0-V battery is in series with a 4.00-Ohm resistor and an unknown resistor. (All three are in one unbranching current loop.) If there is an 8.00-V drop over the 4.00-Ohm resistor, what is the resistance of the second resistor? (20.7)

Explanation / Answer

1) The resistance is given by (rho) * l / A

If length is half and cross section is doubled, the resistance becomes 1/4th

Thus, new resistance is 30 * 1/4 = 7.5 ohms

R = 7.5

V = 12 V

I = V/R = 12 / 7.5 = 1.6 A

2)

The drop across 4 ohm resistor = 8.0 V

total potential drop = 24.0 V

Thus drop across unknown resistor = 24 - 8 = 16.0V

The drop value is directly proportional to the resistances. Hence, the resistance = 4 * 2 = 8 ohms

Ans: Unknown resistor = 8 ohm.

Hope this helps.

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

---

---

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