Q. Equal currents are flowing in three infinitely long wires along positive x, y and z directions. The magnetic field at a point (0, 0, -a) would be (*i* = current in each wire )

(a)

(b)

(c)

(d)

Ans: (a)

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# Tag: Magnetic Effects of Current

## Equal currents are flowing in three infinitely long wires along positive x, y and z directions. The magnetic field at …..

## A tightly-wound long solenoid has n turns per unit length, radius r and carries a current i. A particle having …..

## An equilateral triangle frame PQR of mass M and side a is kept under the influence of magnetic force due to…..

## A wire carrying a current of 3A is bent in the form of a parabola y2 = 4-x as shown in figure …..

## In the figure shown, a charge q moving with a velocity v along the x-axis enter into a region of uniform magnetic field….

Q. Equal currents are flowing in three infinitely long wires along positive x, y and z directions. The magnetic field at a point (0, 0, -a) would be (*i* = current in each wire )

(a)

(b)

(c)

(d)

Ans: (a)

Q. A tightly-wound long solenoid has n turns per unit length, radius r and carries a current *i*. A particle having charge q and mass m is projected from a point on the axis in the direction perpendicular to the axis. The maximum speed for which particle does not strike the solenoid will be

(a)

(b)

(c)

(d) None of these

Ans: (a)

Sol: Magnetic field inside the solenoid is B = μ_{0} n i , along the axis of solenoid

Since velocity is Perpendicular to B , hence particle moves in a circle of radius

If particle does not strike solenoid

R ≤ r/2

Q. An equilateral triangle frame PQR of mass M and side a is kept under the influence of magnetic force due to inward perpendicular magnetic field B and gravitational field as shown in the figure. The magnitude and direction of current in the frame so that the frame remains at rest is

(a) , anticlockwise

(b) , clockwise

(c) , anticlockwise

(d) , clockwise

Ans: (b)

Q. A wire carrying a current of 3A is bent in the form of a parabola y^{2} = 4-x as shown in figure, where x and y are in metre. The wire is placed in a uniform magnetic field tesla . The force acting on the wire is

(a)

(b)

(c)

(d)

Ans: (a)

Sol: y^{2} = 4 – x

At x =0 , y = ± 2

(As , force on parabola is same as force on wire of length L )

Q. In the figure shown, a charge q moving with a velocity v along the x-axis enter into a region of uniform magnetic field. The minimum value of v so that the charge q is able to enter the region x > b

(a)

(b)

(c)

(d)

Ans: (c)