Resistivity

Q.

The resistance of the human body is around

1. $5ohms$

2. $25ohms$

3. $500ohms$

4. $1000ohms$

Q. Resistivity of a material depends on of the conductor.

1. temperature
2. density
3. length

Q. Masses of three wires of copper are in the ratio 1 : 3 : 5 and their lengths are in the ratio of 5 : 3 : 1. The ratio of their electrical resistances are

1. $1:3:5$
2. $5:3:1$
3. $1:15:125$
4. $125:15:1$

Q.

The V-I graph for four different wires of different materials having the same length and diameter are shown in the figure. Which one of the following wire has the highest resistivity?

1. $A$
2. $B$
3. $C$
4. $D$

Q.

If the length of a conductor is increased, its resistivity decreases.

1. False

2. True

Q.

The resistance of a conductor is directly proportional to its

1. Area of cross-section

2. Density

3. Melting point

4. Length

Q. Calculate the resistivity of the material of a wire $2m$ long , $0.4mm$ in diameter and having a resistance $2\Omega$.

1. $1\times {10}^{-7}\Omega -m$
2. $2.5\times {10}^7\Omega -m$
3. $2.5\times {10}^{-7}\Omega -m$
4. $1.25\times {10}^{-7}\Omega -m$

Q.

The resistivity of all pure metals increase with the rise in temperature.

1. True

2. False

Q.

Earth's magnetic field lines are non-uniform while the magnetic field around a bar magnet is uniform:-

1. False

2. True

Q. A resistance R of thermal coefficient of resistivity Alpha is connected in parallel with a resistance 3R having thermal coefficient of resistivity 2Alpha then the equivalent thermal coefficient of resistivity is

Q. The radius of a conducting wire is doubled and length is tripled. What will be the ratio of its new resistivity to the old one? Assume the temperature is constant.

1. $4:3$
2. $3:4$
3. $3:2$
4. $1:1$

Q.

The resistance of a metal wire of length $1m$ is $25\Omega$ at ${20}^{\circ }$ Celsius. If the diameter of the wire is $0.3mm,$ then the resistivity of the wire at that temperature is

1. $4.96\times {10}^{-6}\Omega m$

2. $3.96\times {10}^{-6}\Omega m$

3. $2.96\times {10}^{-6}\Omega m$

4. $1.76\times {10}^{-6}\Omega m$

Q. If the resistivity of the conductor is doubled, then its resistance becomes the original value.

1. half
2. twice
3. three -fourth
4. one - fourth

Q.

What will be the molar conductance ’Λ’, if resistivity is x for 0.1 N H₂SO₄?

1. $\mathrm{\Lambda }=\mathrm{x}\times 1000/0.1$

2. $\mathrm{\Lambda }=2\times 1000/\mathrm{x}\times 0.1$

3. $\mathrm{\Lambda }=\mathrm{x}\times 1000/0.5$

4. $\mathrm{\Lambda }=0.5/1000\mathrm{x}$

Q.

Modem Is A Device Which Performs______.

Q.

Conducting wire of uniform cross sectional area $2c{m}^2$ and length $1cm$ carries a current of $8A$ and has a potential difference of $2V$. The resistivity of the material of the wire is:

1. $0.5\Omega cm$
2. $0.05\Omega cm$
3. $0.5\Omega m$
4. $0.05\Omega m$

Q. A conductor of length L has an uniform cross section the radius of the cross section where is linearly from A to B the resistivity of the material is " r " find the resistance of the conductor across its ends.

Q. Two metal balls of same radius are placed in a homogenous poorly conducting medium with resistivity "r" find resistance if they are seperated by a large distance .(the balls are oppositely charged).

Q.

If the shape of the wire is changed , will the resistance change?Explain

Q.

A thinner brass wire will always have more resistance than a thicker bronze wire.

1. True

2. False

Q.

On what factors does the resistance of a conductor depend? [2 MARKS]

Q.

The resistivity of all pure metals increases with the rise in temperature.

Q. A wire has a resistance of $10\Omega$. It is stretched by $1/10$ of its original length. Then its resistance will be

1. $9\Omega$
2. $10\Omega$
3. $11\Omega$
4. $12.1\Omega$

Q.

Conducting wire of uniform cross sectional area $2c{m}^2$ and length $1cm$ carries a current of $8A$ and has a potential difference of $2V$. The resistivity of the material of the wire is:

1. $0.5\Omega m$
2. $0.05\Omega m$
3. $0.05\Omega cm$
4. $0.5\Omega cm$

Q. The resistance of a 20 cm long wire is 5 $\Omega$. The wire is stretched to form a uniform wire of 40 cm length. The resistance now will be :

1. $5\Omega$
2. $20\Omega$
3. $10\Omega$
4. $200\Omega$

Q. Find the resistivity of the given resistor of resistance $25\Omega$?

1. $125\Omega m$
2. $1.25\Omega m$
3. $12.5\Omega m$
4. $1.5\Omega m$

Q. Sort the elements according to the increasing order of their resistivities.

1. Aluminium ore
2. Silver
3. Iron
4. Tungsten
5. Carbon

Q. Calculate the voltage across bulb B3.

1. a
2. b
3. c
4. d

Q.

The unit of resistivity is ____________

1. ohm

2. mho

3. ohm/m

4. ohm-m

Q.

a given wire having restistance R is streched so as to reduce its diameter to half of its previous value. wat will be the new resistance?