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Q. No.A model for the quantized motion of an electron in a uniform magnetic field \(B\) states that the flux passing through the orbit of the electron is \(n(h/e)\) where \(n\) is an integer, \(h\) is Planck's constant and \(e\) is the magnitude of the electron's charge. According to the model, the magnetic moment of an electron is its lowest energy state will be (\(m\) is the mass of the electron):
| 1. | \(\dfrac{heB}{\pi m}\) | 2. | \(\dfrac{heB}{2\pi m}\) |
| 3. | \(\dfrac{he}{\pi m}\) | 4. | \(\dfrac{he}{2\pi m}\) |
Subtopic: Magnetic Moment |
From NCERT
NEET - 2025
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An electron (mass \(9\times10^{-31}~\text{kg}\) and charge \(1.6\times10^{-19}~\text C\)) moving with speed \(c/100\) (\(c\)=speed of light) is injected into a magnetic field \(\vec B\) of magnitude \(9\times10^{-4}~\text{T}\) perpendicular to its direction of motion. We wish to apply an uniform electric field \(\vec E\) together with the magnetic field so that the electron does not deflect from its path. Then (speed of light \(c=3\times10^8~\text{ms}^{-1}\))
| 1. | \(\vec E\) is parallel to \(\vec B\) and its magnitude is \(27\times10^{2}~\text{V m}^{-1}\) |
| 2. | \(\vec E\) is parallel to \(\vec B\) and its magnitude is \(27\times10^{4}~\text{V m}^{-1}\) |
| 3. | \(\vec E\) is perpendicular to \(\vec B\) and its magnitude is \(27\times10^{4}~\text{V m}^{-1}\) |
| 4. | \(\vec E\) is perpendicular to \(\vec B\) and its magnitude is \(27\times10^{2}~\text{V m}^{-1}\) |
Subtopic: Lorentz Force |
From NCERT
NEET - 2025
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A \(2~\text{amp}\) current is flowing through two different small circular copper coils having radii ratio \(1:2.\) The ratio of their respective magnetic moments will be:
1. \(2: 1\)
2. \(4: 1\)
3. \(1: 4\)
4. \(1: 2\)
1. \(2: 1\)
2. \(4: 1\)
3. \(1: 4\)
4. \(1: 2\)
Subtopic: Magnetic Moment |
66%
From NCERT
NEET - 2025
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A tightly wound \(100\) turns coil of radius \(10~\text{cm}\) carries a current of \(7~\text A\). The magnitude of the magnetic field at the centre of the coil is: (Take permeability of free space as \(4 \pi \times 10^{-7}\)SI units):
1. \(4.4~\text T\)
2. \(4.4~\text {mT}\)
3. \(44~\text T\)
4. \(44~\text {mT}\)
1. \(4.4~\text T\)
2. \(4.4~\text {mT}\)
3. \(44~\text T\)
4. \(44~\text {mT}\)
Subtopic: Magnetic Field due to various cases |
71%
From NCERT
NEET - 2024
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A wire carrying a current \(I\) along the positive \(x\)-axis has length \(L\). It is kept in a magnetic field \(\overrightarrow{B}=(2 \hat{i}+3 \hat{j}-4 \hat{k})~\text{T}\). The magnitude of the magnetic force acting on the wire is:
1. \(\sqrt{3}IL\)
2. \(3IL\)
3. \(\sqrt{5}IL\)
4. \(5IL\)
1. \(\sqrt{3}IL\)
2. \(3IL\)
3. \(\sqrt{5}IL\)
4. \(5IL\)
Subtopic: Lorentz Force |
64%
From NCERT
NEET - 2023
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A very long conducting wire is bent in a semi-circular shape from \(A\) to \(B\) as shown in the figure. The magnetic field at the point \(P\) for steady current configuration is given by:
| 1. | \(\dfrac{\mu_0 i}{4 R}\left[1-\dfrac{2}{\pi}\right]\) pointed into the page |
| 2. | \(\dfrac{\mu_0 i}{4 R}\) pointed into the page |
| 3. | \(\dfrac{\mu_0 i}{4 R}\) pointed away from the page |
| 4. | \(\dfrac{\mu_0 i}{4 R}\left[1-\dfrac{2}{\pi}\right]\) pointed away from the page |
Subtopic: Magnetic Field due to various cases |
57%
From NCERT
NEET - 2023
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A long straight wire of length \(2\) m and mass \(250\) g is suspended horizontally in a uniform horizontal magnetic field of \(0.7\) T. The amount of current flowing through the wire will be:
(\(g=9.8~\text{ms}^{-2}\))
1. \(2.45\) A
2. \(2.25\) A
3. \(2.75\) A
4. \(1.75\) A
(\(g=9.8~\text{ms}^{-2}\))
1. \(2.45\) A
2. \(2.25\) A
3. \(2.75\) A
4. \(1.75\) A
Subtopic: Lorentz Force |
78%
From NCERT
NEET - 2023
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A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron:
| 1. | will turn towards right of direction of motion |
| 2. | will turn towards left of direction of motion |
| 3. | speed will decrease |
| 4. | speed will increase |
Subtopic: Lorentz Force |
65%
From NCERT
NEET - 2023
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A long solenoid of radius \(1~\text{mm}\) has \(100\) turns per mm. If \(1~\text{A}\) current flows in the solenoid, the magnetic field strength at the centre of the solenoid is:
| 1. | \(6.28 \times 10^{-4} ~\text{T} \) | 2. | \(6.28 \times 10^{-2}~\text{T}\) |
| 3. | \(12.56 \times 10^{-2}~\text{T}\) | 4. | \(12.56 \times 10^{-4} ~\text{T}\) |
Subtopic: Magnetic Field due to various cases |
65%
From NCERT
NEET - 2022
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Given below are two statements:
| Statement I: | Biot-Savart's law gives us the expression for the magnetic field strength of an infinitesimal current element \((Idl)\) of a current-carrying conductor only. |
| Statement II: | Biot-Savart's law is analogous to Coulomb's inverse square law of charge \(q,\) with the former being related to the field produced by a scalar source, \((Idl)\) while the latter being produced by a vector source, \(q.\) |
| 1. | Statement I is incorrect but Statement II is correct. |
| 2. | Both Statement I and Statement II are correct. |
| 3. | Both Statement I and Statement II are incorrect. |
| 4. | Statement I is correct but Statement II is incorrect. |
Subtopic: Biot-Savart Law |
55%
From NCERT
NEET - 2022
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