Three long, straight parallel wires carrying current, are arranged as shown in figure. The force experienced by a 25 cm length of wire C is

(a) ${10}^{-3}N$

(b) $2.5×{10}^{-3}N$

(c) Zero

(d) $1.5×{10}^{-3}N$

Concept Questions :-

Force between current carrying wires
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A 250-turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85$\mu$A and subjected to a magnetic field of strength o.85 T. Work done for rotating the coil by ${180}^{\circ }$ against the torque is

(a) 9.1 $\mu J$

(b) 4.55$\mu J$

(c) 2.3$\mu$$J$

(d) 1.5$\mu J$

Concept Questions :-

Magnetic moment
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

An arrangement of three parallel straight wires placed perpendicular to the plane of paper carrying the same current I along the same direction as shown in the figure. Magnitude of force per unit length on the middle wire B is given by:

1. $\frac{{\mu }_{o}{i}^{2}}{2\mathrm{\pi d}}$

2. $\frac{2{\mu }_{0}{i}^{2}}{\mathrm{\pi d}}$

3. $\frac{\sqrt{2}{\mu }_{o}{i}^{2}}{\pi d}$

4. $\frac{{\mu }_{o}{i}^{2}}{\sqrt{2}\mathrm{\pi d}}$

Concept Questions :-

Magnetic field due to various cases
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the center of loop is B. It is then bent into a circular coil of n turns. The magnetic field at the centre of this coil of n turns will be

(a) nB                (b) ${n}^{2}B$

(c) 2nB              (d) $2{n}^{2}B$

Concept Questions :-

Magnetic field due to various cases
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

An electron is moving in a circular path under the influence of a transverse magnetic field of $3.57×{10}^{-2}$ T. If the value of e/m is $1.76×{10}^{11}$ C/kg, the frequency of revolution of the electron is

(a) 1 GHz              (b) 100 MHz

(c) 62.8 MHz         (d) 6.28 MHz

Concept Questions :-

Lorentz force
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A square loop ABCD carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current I, the net force on the loop will be:

1. $\frac{{\mu }_{0}Ii}{2\mathrm{\pi }}$              2. $\frac{2{\mu }_{0}IiL}{3\mathrm{\pi }}$

3. $\frac{{\mu }_{0}IiL}{2\mathrm{\pi }}$            4. $\frac{2{\mu }_{0}Ii}{3\mathrm{\pi }}$

Concept Questions :-

Current carrying loop : Force and torque
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A long straight wire of radius a carries a steady current I. The current is uniformly distributed over its cross-section. The ratio of the magnetic fields B and B' at radial distances a/2 and 2a respectively, from the axis of the wire, is:

1. 1/2

2. 1

3. 4

4. 1/4

Concept Questions :-

Magnetic field due to various cases
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A wire carrying current l has the shape as shown in the adjoining figure. Linear parts of the wire are very long and parallel to X-axis while the semicircular portion of radius R is lying in the Y-Z plane. Magnetic field at point O is :

1. $\mathrm{B}=\frac{{\mathrm{\mu }}_{0}}{4\mathrm{\pi }}×\frac{\mathrm{i}}{\mathrm{R}}\left(\mathrm{\pi }\stackrel{^}{\mathrm{i}}+2\stackrel{^}{\mathrm{k}}\right)$

2. $\mathrm{B}=-\frac{{\mathrm{\mu }}_{0}}{4\mathrm{\pi }}×\frac{\mathrm{i}}{\mathrm{R}}\left(\mathrm{\pi }\stackrel{^}{\mathrm{i}}-2\stackrel{^}{\mathrm{k}}\right)$

3. $\mathrm{B}=-\frac{{\mathrm{\mu }}_{0}}{4\mathrm{\pi }}×\frac{\mathrm{i}}{\mathrm{R}}\left(\mathrm{\pi }\stackrel{^}{\mathrm{i}}+2\stackrel{^}{\mathrm{k}}\right)$

4. $\mathrm{B}=\frac{{\mathrm{\mu }}_{0}}{4\mathrm{\pi }}×\frac{\mathrm{i}}{\mathrm{R}}\left(\mathrm{\pi }\stackrel{^}{\mathrm{i}}-2\stackrel{^}{\mathrm{k}}\right)$

Concept Questions :-

Magnetic field due to various cases
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude:

Concept Questions :-

Lorentz force
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A proton and an alpha particle both enter a region of uniform magnetic field B, moving at right angles to the field B. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is 1 MeV, the energy acquired by the alpha particle will be

(a)4 MeV

(b) 0.5 MeV

(c) 1.5 MeV

(d) 1 MeV

Concept Questions :-

Lorentz force