Advertisements
Advertisements
प्रश्न
A negligibly small current is passed through a wire of length 15 m and uniform cross-section 6.0 × 10−7 m2, and its resistance is measured to be 5.0 Ω. What is the resistivity of the material at the temperature of the experiment?
Advertisements
उत्तर
Length of the wire, l = 15 m
Area of cross-section of the wire, A = 6.0 × 10−7 m2
Resistance of the material of the wire, R = 5.0 Ω
Resistivity of the material of the wire ρ = ?
Resistance is related to resistivity as
R = `ρ "l"/"A"`
ρ = `("RA")/"l"`
= `(5 xx 6 xx 10^-7)/15`
= 2 × 10−7 Ω m
Therefore, the resistivity of the material is 2 × 10−7 Ω m.
APPEARS IN
संबंधित प्रश्न
Two wires of equal length, one of aluminium and the other of copper have the same resistance. Which of the two wires is lighter? Hence explain why aluminium wires are preferred for overhead power cables.
(ρAl = 2.63 × 10−8 Ω m, ρCu = 1.72 × 10−8 Ω m, Relative density of Al = 2.7, of Cu = 8.9.)
What conclusion can you draw from the following observations on a resistor made of alloy manganin?
| Current A |
Voltage V |
Current A |
Voltage V |
| 0.2 | 3.94 | 3.0 | 59.2 |
| 0.4 | 7.87 | 4.0 | 78.8 |
| 0.6 | 11.8 | 5.0 | 98.6 |
| 0.8 | 15.7 | 6.0 | 118.5 |
| 1.0 | 19.7 | 7.0 | 138.2 |
| 2.0 | 39.4 | 8.0 | 158.0 |
Choose the correct alternative:
Alloys of metals usually have (greater/less) resistivity than that of their constituent metals.
A heating element is marked 210 V, 630 W. What is the value of the current drawn by the element when connected to a 210 V dc source?
A heating element is marked 210 V, 630 W. Find the resistance of the element when connected to a 210 V dc source.
Two resistors A and B have resistances RA and RB, respectively, and RA < RB. The resistivities of their materials are ρA and ρB.
A uniform wire of resistance 100 Ω is melted and recast as a wire whose length is double that of the original. What would be the resistance of the wire?
What length of a copper wire of cross-sectional area 0.01 mm2 will be needed to prepare a resistance of 1 kΩ? Resistivity of copper = 1.7 × 10–8 Ωm
The electrochemical equivalent of a material depends on _______________ .
How does the resistivity of a semiconductor change with rise of temperature ? Explain.
If R1 and R2 are filament resistances of a 200 W and a 100 W bulb respectively, designed to operate on the same voltage, then:
Choose the correct alternative:
Alloys usually have much (lower/higher) temperature coefficients of resistance than pure metals.
The resistivity of alloy manganin is ______.
If the last band on the carbon resistor is absent, then the tolerance is ______
