- 1(current)
Q. No.A uniform wire of diameter \(d\) carries a current of \(100~\text{mA}\) when the mean drift velocity of electrons in the wire is \(v.\) For a wire of diameter \({\dfrac{d}{2}}\) of the same material to carry a current of \(200~\text{mA},\) the mean drift velocity of electrons in the wire is:
| 1. | \(4v\) | 2. | \(8v\) |
| 3. | \(v\) | 4. | \(2v\) |
Subtopic: Â Current & Current Density |
 70%
Level 2: 60%+
NEET - 2024
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A uniform metal wire of length \(l\) has \(10~\Omega \) resistance. Now this wire is stretched to a length \(2l\) and then bent to form a perfect circle. The equivalent resistance across any arbitrary diameter of that circle is:
| 1. | \(10~\Omega \) | 2. | \(5~\Omega \) |
| 3. | \(40~\Omega \) | 4. | \(20~\Omega \) |
Subtopic: Â Current & Current Density |
 50%
Level 3: 35%-60%
NEET - 2024
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A copper wire of radius \(1\) mm contains \(10^{22}\) free electrons per cubic metre. The drift velocity for free electrons when \(10\) A current flows through the wire will be:
(Given, charge on electron = \(1.6\times10^{-19}\) C)
(Given, charge on electron = \(1.6\times10^{-19}\) C)
| 1. | \(\dfrac{6.25\times10^4}{\pi}\) m/s | 2. | \(\dfrac{6.25}{\pi}\times10^3\) m/s |
| 3. | \(\dfrac{6.25}{\pi}\) m/s | 4. | \(\dfrac{6.25\times10^5}{\pi}\) m/s |
Subtopic: Â Current & Current Density |
 74%
Level 2: 60%+
NEET - 2023
Hints
A copper wire of length \(10\) m and radius \(\left({10^{-2}/\sqrt{\pi}}\right)\) m has an electrical resistance of \(10~\Omega.\) The current density in the wire for an electric field strength of \(10\) (V/m) is:
1. \(10^{5}\) A/m2
2. \(10^{4}\) A/m2
3. \(10^{6}\) A/m2
4. \(10^{-5}\) A/m2
1. \(10^{5}\) A/m2
2. \(10^{4}\) A/m2
3. \(10^{6}\) A/m2
4. \(10^{-5}\) A/m2
Subtopic: Â Current & Current Density |
 68%
Level 2: 60%+
NEET - 2022
Hints
Match Column I and Column II with appropriate relations.
| Column I | Column II | ||
| (A) | Drift Velocity | (P) | \(\dfrac{ \mathrm{m}}{\mathrm{ne}^2 \rho}\) |
| (B) | Electrical Resistivity | (Q) | \(nev_d\) |
| (C) | Relaxation Period | (R) | \(\dfrac{ \mathrm{eE}}{\mathrm{m}} \tau\) |
| (D) | Current Density | (S) | \(\dfrac{E}{J}\) |
| (A) | (B) | (C) | (D) | |
| 1. | (R) | (P) | (S) | (Q) |
| 2. | (R) | (Q) | (S) | (P) |
| 3. | (R) | (S) | (P) | (Q) |
| 4. | (R) | (S) | (Q) | (P) |
Subtopic: Â Current & Current Density |
 57%
Level 3: 35%-60%
NEET - 2021
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A charged particle having drift velocity of \(7.5\times10^{-4}~\text{ms}^{-1}\) in an electric field of \(3\times10^{-10}~\text{Vm}^{-1},\) has mobility of:
1. \(2.5\times 10^{6}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)
2. \(2.5\times 10^{-6}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)
3. \(2.25\times 10^{-15}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)
4. \(2.25\times 10^{15}~\text{m}^2\text{V}^{-1}\text{s}^{-1}\)
Subtopic: Â Current & Current Density |
 83%
Level 1: 80%+
NEET - 2020
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- 1(current)
Q. No.
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