In a conductor 4 coulombs of charge flows for 2 seconds. The value of electric current will be :

1. 4 volts

2. 4 amperes

3. 2 amperes

4. 2 volts

The specific resistance of a wire is ρ, its volume is 3 m³ and its resistance is 3 ohms, then its length will be 

1. $\sqrt{\frac{1}{\rho }}$

2. $\frac{3}{\sqrt{\rho }}$

3. $\frac{1}{\rho }\sqrt{3}$

4. $\rho \sqrt{\frac{1}{3}}$ 

When a piece of aluminum wire of finite length is drawn through a series of dies to reduce its diameter to half its original value, its resistance will become :

1. Two times

2. Four times

3. Eight times

4. Sixteen times

Through a semiconductor, an electric current is due to drift off:

1. Free electrons

2. Free electrons and holes

3. Positive and negative ions

4. Protons

The specific resistance of all metals is most affected by :

1. Temperature

2. Pressure

3. Degree of illumination

4. Applied magnetic field

The positive temperature coefficient of resistance is for :

1. Carbon

2. Germanium

3. Copper

4. An electrolyte

The electric intensity $E,$ current density $j$ and specific resistance $k$ are related to each other by the relation:
1. $E = j/k$
2. $E = jk$
3. $E = k/j$
4. $k = j E$

The resistance of a wire of uniform diameter d and length L is R. The resistance of another wire of the same material but diameter 2d and length 4L will be :

1. 2R

2. R

3. R/2

4. R/4