1
NEET 2025
MCQ (Single Correct Answer)
+4
-1
Change Language

An electron (mass $9 \times 10^{-31} \mathrm{~kg}$ and charge $1.6 \times 10^{-19} \mathrm{C}$ ) moving with speed $c / 100(c=$ speed of light) is injected into a magnetic field $\vec{B}$ of magnitude $9 \times 10^{-4} \mathrm{~T}$ 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 $c=3$ $\times 10^3 \mathrm{~ms}^{-1}$)

A
$\vec{E}$ is parallel to $\vec{B}$ and its magnitude is $27 \times 10^2 \mathrm{~V} \mathrm{~m}^{-1}$
B
$\vec{E}$ is parallel to $\vec{B}$ and its magnitude is $27 \times 10^4 \mathrm{~V} \mathrm{~m}^{-1}$
C
$\vec{E}$ is perpendicular to $\vec{B}$ and its magnitude is $27 \times 10^4 \mathrm{~V} \mathrm{~m}^{-1}$
D
$\vec{E}$ is perpendicular to $\vec{B}$ and its magnitude is $27 \times 10^2 \mathrm{~V} \mathrm{~m}^{-1}$
2
NEET 2025
MCQ (Single Correct Answer)
+4
-1
Change Language

A 2 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

A
$2: 1$
B
$4: 1$
C
$1: 4$
D
$1: 2$
3
NEET 2024
MCQ (Single Correct Answer)
+4
-1
Change Language

A tightly wound 100 turns coil of radius $$10 \mathrm{~cm}$$ carries a current of $$7 \mathrm{~A}$$. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as $$4 \pi \times 10^{-7} \mathrm{SI}$$ units):

A
44 mT
B
4.4 T
C
4.4 mT
D
44 T
4
NEET 2024
MCQ (Single Correct Answer)
+4
-1
Change Language

A parallel plate capacitor is charged by connecting it to a battery through a resistor. If $$I$$ is the current in the circuit, then in the gap between the plates:

A
There is no current
B
Displacement current of magnitude equal to $$I$$ flows in the same direction as $$I$$
C
Displacement current of magnitude equal to $$I$$ flows in a direction opposite to that of $$I$$
D
Displacement current of magnitude greater than $$I$$ flows but can be in any direction
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