Which of the following graph correctly represents the variation of mobility $\left(\mathrm{\mu }\right)$ of electrons with applied electric field (E) in a metallic conductor?

1.		2.
3.		4.

A current of 1 mA is flowing through a copper wire. How many electrons will pass a given point in one second  $\left[\mathrm{e} = 1.6 \times {10}^{-19} \mathrm{Coulomb}\right]$

1.  $6.25 \times {10}^{19}$

2.  $6.25 \times {10}^{15}$

3.  $6.25 \times {10}^{31}$

4.  $6.25 \times {10}^8$

The drift velocity of free electrons in a conductor is \(v\) when a current \(i\) is flowing in it. If both the radius and current are doubled, then the drift velocity will be:
1.  \(v\)
2. \(\frac{v}{2}\)$$
3. \(\frac{v}{4}\)$$
4. \(\frac{v}{8}\)

Drift velocity v_d varies with the intensity of electric field as per the relation: 

1. $v_d\propto E$

2. $v_d\propto \frac{1}{E}$

3. v_d = constant

4. $v_d\propto E^2$ 

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

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

If a metallic block has no potential difference applied across it, then the mean velocity of free electron is:
(T = absolute temperature of the block)

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 = jE

There is a current of 1.344 amp in a copper wire whose area of cross-section normal to the length of the wire is 1 mm². If the number of free electrons per cm³ is 8.4 × 10²², then the drift velocity would be :

1. 1.0 mm/sec

2. 1.0 m/sec

3. 0.1 mm/sec

4. 0.01 mm/sec