Factors affecting Resistance &Â How they affectÂ

Q.

What is the relation between conductance and conductivity?

Q.

Define the resistivity of a conductor.

Q.

Is resistivity directly proportional to the resistance?

Q.

The electrical resistivity of a given metallic wire depends upon

1. its length

2. its thickness

3. its shape

4. nature of the material

Q.

Define the Term Resistivity of Material?

Q.

The resistance if a wire is R ohm. If it is melted and stretched to n times its original length, its new resistance will be:

Q.

A wire 1 m long has a resistances of 1Ω. If it is uniformly stretched, so that its length increases by 25%, then its resistance will increase by:

1. 25%

2. 50%

3. 56.25%

4. 77.33%

Q. Water boils in the electric kettle in 1.5 minutes after switching on. If the length of heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in

1. 0.8 minutes
2. 1 minutes
3. 1.2 minutes
4. 1.5 minutes

Q. Which among the following equation gives the correct relation between resistance $\left(R\right)$, length of conductor $\left(L\right)$, area of the cross-section of the conductor $\left(A\right)$ and resistivity$\left(\rho \right)$?

1. $R=\frac{L}{A\times \rho }$

2. $R=\frac{A\times \rho }{L}$

3. $R=\frac{\rho \times L}{A}$

4. $R=\frac{A\times L}{\rho }$

Q.

You have a metal wire of length 1000 m, radius of 0.7 mm andresistivity of the metal is given as $153.86\times {10}^{-6}\Omega m$. Find the resistance of the wire.

1. $100k\Omega$
2. $40k\Omega$
3. $18k\Omega$
4. $250k\Omega$

Q.

If a metallic wire of resistance R is melted and recast to half of its length, the new resistance of the wire will be?

1. $\frac{R}{4}$

2. $\frac{R}{2}$

3. R

4. 2R

Q. A longer wire has a higher resistance than a ___ wire of the same thickness and same material.

Q.

In a circuit two resistances of the same material and cross section area but different length $L_1$ & $L_2$ are kept in series. Find the length of the equivalent resistance if it’s made of the same material and same cross section area.

1. L1xL2/(L1+L2)

2. L1-L2

3. 1/L1 + 1/L2

4. L1+L2

Q.

Certain wire has resistance of 10 Ohm. If it is stretched by 1/10th of its length, then its resistance is nearly:

1. 9 Ω

2. 10 Ω

3. 11 Ω

4. 12 Ω

Q.

A metal wire of resistance $6\Omega$is stretched so that its length is increased to twice its original length. Calculate its new resistance.

Q. A certain x-ray tube operates at a current of $7.00$ mA and a
potential difference of $80.0$ kV. What is its power in watts?

Q.

If an increase in the length of copper wire is 25% due to stretching, the percentage increase in its resistance will be:

1. 1%

2. 0.2%

3. 1%

4. 2%

Q.

A wire of resistance $2\Omega$ is stretched to double its length such that its volume remains constant. What is the resistance of the stretched wire?

1. $2\Omega$
2. $8\Omega$
3. $6\Omega$
4. $14.75\Omega$

Q.

Thicker wire will have more resistance than a thinner wire.

1. True

2. False

Q.

A wire has a diameter of 0.5 mm and a resistivity of 1.6 × ${10}^{-6}$ ohm cm. How much of this wire would be required to make a 10 ohm coil?

1. 1000 m

2. 112.7 m

3. 157.6 m

4. 57 m