Physics · Current Electricity
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0.75 A current flows through an iron wire when a battery of 1.5 volts is connected across its ends. The length of the wire 5.0 m and its cross-sectional area is 2.5 x 10-7 m2. What is the resistivity of iron?
- A
9.0 x 10-7 Ωm
- B
7.0 x 10-7 Ωm
- C
5.0 x 10-7 Ωm
- D
3.0 x 10-7 Ωm
- E
1.0 x 10-7 Ωm
To solve this problem, start by using Ohm's law, V = IR, to find the resistance (R). Given V = 1.5 V and I = 0.75 A, R = V/I = 1.5 V / 0.75 A = 2 Ω.
Next, use the formula for resistivity (resistivity = R × A / l), where A is the cross-sectional area (2.5 × 10-7 m2) and l is the length of the wire (5.0 m). Plugging in the values, resistivity = 2 Ω × (2.5 × 10-7 m2) / 5.0 m = 1.0 × 10-7 Ωm.
Thus, the correct answer is 1.0 x 10-7 Ωm. The other options result from errors in applying the formulas or calculations.
This value is incorrect. You might have miscalculated the resistance or the resistivity using incorrect values or formulas.
This is not the right answer. Double-check your calculations for resistance and ensure you used the correct length and cross-sectional area in the resistivity formula.
This value is incorrect. Be sure you're applying Ohm's law and the resistivity formula accurately with the given measurements.
This is not correct. Verify that you have used the formula for resistivity properly with the correct values for current and voltage.
This is the correct answer. By using the formula R = V/I to calculate resistance, and then applying the resistivity formula (resistivity = R * A / l), you arrive at this value.
Tagged under Physics · Current Electricity