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. $$44~\text {mT}$$
Subtopic:  Magnetic Field due to various cases |
68%
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 $$\vec{B}=(2 \hat{i}+3 \hat{j}-4 \hat{k})~\text{T}$$. The magnitude of the magnetic force acting on the wire is:
1. $$\sqrt{3}IL$$
2. $$3IL$$
3. $$\sqrt{5}IL$$
4. $$5IL$$
Subtopic:  Lorentz Force |
59%
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 point $$P$$ for steady current configuration is given by:

 1 $$\frac{\mu_0 i}{4 R}\left[1-\frac{2}{\pi}\right]$$ pointed into the page 2 $$\frac{\mu_0 i}{4 R}$$ pointed into the page 3 $$\frac{\mu_0 i}{4 R}$$ pointed away from the page 4 $$\frac{\mu_0 i}{4 R}\left[1-\frac{2}{\pi}\right]$$ pointed away from the page
Subtopic:  Magnetic Field due to various cases |
52%
From NCERT
NEET - 2023
Hints

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
Subtopic:  Lorentz Force |
75%
From NCERT
NEET - 2023
Hints

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 |
61%
From NCERT
NEET - 2023
Hints

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 |
63%
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 $$I(dl)$$ 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 false but Statement II is true. 2 Both Statement I and Statement II are true. 3 Both Statement I and Statement II are false. 4 Statement I is true but Statement II is false.
Subtopic:  Biot-Savart Law |
52%
From NCERT
NEET - 2022
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From Ampere's circuital law, for a long straight wire of circular cross-section carrying a steady current, the variation of the magnetic field inside and outside the region of the wire is:
 1 a linearly decreasing function of distance upto the boundary of the wire and then a linearly increasing one for the outside region. 2 uniform and remains constant for both regions. 3 a linearly increasing function of distance upto the boundary of the wire and then a linearly decreasing one for the outside region. 4 a linearly increasing function of distance $$r$$ upto the boundary of the wire and then decreasing one with $$1/r$$ dependence for the outside region.
Subtopic:  Ampere Circuital Law |
62%
From NCERT
NEET - 2022
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The ratio of the radii of two circular coils is $$1:2$$. The ratio of currents in the respective coils such that the same magnetic moment is produced at the centre of each coil is:
1. $$4:1$$
2. $$2:1$$
3. $$1:2$$
4. $$1:4$$

Subtopic:  Magnetic Moment |
61%
From NCERT
NEET - 2022
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A strong magnetic field is applied along the direction of the velocity of an electron. The electron would move along:

 1 a parabolic path 2 the original path 3 a helical path 4 a circular path
Subtopic:  Lorentz Force |
65%
From NCERT
NEET - 2022
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