Which of the following graph correctly represents the variation of mobility \((\mu)\) 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
1.
2.
3.
4.
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. | \(\dfrac{v}{2}\) |
| 3. | \(\dfrac{v}{4}\) | 4. | \(\dfrac{v}{8}\) |
Drift velocity \(v_d\) varies with the intensity of the electric field as per the relation:
1. \(v_{d} \propto E\)
2. \(v_{d} \propto \frac{1}{E}\)
3. \(v_{d}= \text{constant}\)
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
(\(T\)= absolute temperature of the block)
| 1. | proportional to \(T\). | 2. | proportional to\(\sqrt{T} \) |
| 3. | zero. | 4. | finite but independent of temperature. |
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. \(k = j E\)
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
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