Energy Band Diagram

Q. If the ratio of the concentration of electrons to that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of current is $\frac{7}{4},$ then the ratio of their drift velocities is $\frac{N}{8}.$ The value of $N$(integer only)

Q. A potential difference of $6\text{V}$ is applied across a conductor of length $0.12\text{m}$. The drift velocity of an electron is
$[$mobility of electron$=5.6\times {10}^{-6}{\text{m}}^2\text{/Vs}]$

1. $1.4\times {10}^{-4}\text{m/s}$
2. $2.8\times {10}^{-6}\text{m/s}$
3. $5.6\times {10}^{-4}\text{m/s}$
4. $2.8\times {10}^{-4}\text{m/s}$

Q. A current of $5\text{A}$ passes through a copper conductor (resistivity = $1.7\times {10}^{-8}\Omega \text{m})$ of radius of cross-section $5\text{mm}$. Find the mobility of the charges, if their drift velocity is $1.1\times {10}^{-3}\text{m/s}.$

1. $1.0{\text{m}}^2/\text{Vs}$
2. $1.5{\text{m}}^2/\text{Vs}$
3. $1.3{\text{m}}^2/\text{Vs}$
4. $1.8{\text{m}}^2/\text{Vs}$

Q. A potential difference $V$ is applied to a copper wire of length $l$ and radius $r$. If $V$ is doubled, the drift velocity

1. is doubled
2. is halved
3. remains same
4. becomes zero

Q. If the ratio of the concentration of electron to that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of currents is $\frac{7}{4}$, then what is the ratio of their drift velocities-

1. $\frac{5}{4}$
2. $\frac{4}{7}$
3. $\frac{4}{5}$
4. $\frac{5}{8}$

Q. There is a current of $20\text{A}$ in a wire of cross-sectional area $0.01{\text{cm}}^2$. If number of free electrons per cubic metre is ${10}^{29}$, then the drift velocity will be

1. $1.25\times {10}^3{\text{ms}}^{-1}$
2. $2.5\times {10}^{-3}{\text{ms}}^{-1}$
3. $2.5\times {10}^{-4}{\text{ms}}^{-1}$
4. $1.25\times {10}^{-3}{\text{ms}}^{-1}$

Q. Across a conductor of length $40\text{cm}$, a potential difference of $10\text{V}$ is maintained. The mobility of electrons if the drift velocity of electrons is $5\times {10}^{-6}\text{m/s}$ is

1. $2\times {10}^{-7}{\text{m}}^2\text{/Vs}$
2. $1\times {10}^{-7}{\text{m}}^2\text{/Vs}$
3. $4\times {10}^{-6}{\text{m}}^2\text{/Vs}$
4. $0.5\times {10}^{-7}{\text{m}}^2\text{/Vs}$

Q. A current of $5\text{A}$ is passing through a metallic wire of cross sectional area $14\times {10}^{-6}{\text{m}}^2$. If the density of the charge carries in the wire is $5\times {10}^{26}{\text{C/m}}^3$, the drift speed of the electrons.

1. $3.46\times {10}^{-3}{\text{ms}}^{-1}$
2. $4.46\times {10}^{-3}{\text{ms}}^{-1}$
3. $5.46\times {10}^{-3}{\text{ms}}^{-1}$
4. $6.46\times {10}^{-3}{\text{ms}}^{-1}$

Q. In copper, each atom releases one electron. If a current of 1.1A is flowing in the copper wire of diameter 1mm then the drift velocity of electrons, will approximately be (density of copper $=9\times {10}^{3}Kg{m}^{-3}$ and its atomic weight $=63)$.

1. 0.1 mm/s
2. 0.2 cm/s
3. 0.2 mm/s
4. 10.3 mm/s

Q. A potential difference of $6\text{V}$ is applied across a conductor of length $0.12\text{m}$. The drift velocity of an electron is
$[$mobility of electron$=5.6\times {10}^{-6}{\text{m}}^2\text{/Vs}]$

1. $1.4\times {10}^{-4}\text{m/s}$
2. $2.8\times {10}^{-6}\text{m/s}$
3. $5.6\times {10}^{-4}\text{m/s}$
4. $2.8\times {10}^{-4}\text{m/s}$

Q. If the ratio of the concentration of electrons to that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of corresponding currents is $\frac{7}{4}$ then what is the ratio of their drift velocities ?

1. $\frac{5}{8}$
2. $\frac{4}{5}$
3. $\frac{5}{4}$
4. $\frac{4}{7}$

Q. If the ratio of the concentration of electrons to that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of current is $\frac{7}{4},$ then the ratio of their drift velocities is $\frac{N}{8}.$ The value of $N$(integer only)

Q. Across a conductor of length $40\text{cm}$, a potential difference of $10\text{V}$ is maintained. The mobility of electrons if the drift velocity of electrons is $5\times {10}^{-6}\text{m/s}$ is

1. $2\times {10}^{-7}{\text{m}}^2\text{/Vs}$
2. $1\times {10}^{-7}{\text{m}}^2\text{/Vs}$
3. $4\times {10}^{-6}{\text{m}}^2\text{/Vs}$
4. $0.5\times {10}^{-7}{\text{m}}^2\text{/Vs}$

Q. In the given figure, a battery of emf \(E\) is connected across a conductor \(\text{PQ}\) of length \(l\) and different area of cross-sections having radii \(r_1\) and \(r_2~(r_2<r_1)\).


Choose the correct option as one moves from \(\text P\) to \(\text Q\) :