M.C.Q : Magnetic Effect Of Current ( 1 to 1 0 )

LEVEL – I

1. Two thin long parallel wires separated by a distance b are carrying a current i amp each. The magnitude of the force per unit length exerted by one wire on the other is:

(A) μo(i2/b2)

(B)μoi2/2πb

(C) πoi/2πb

(D) μoi/4πb

2. A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to one of the sides of the loop and is in the plane of the loop. If a steady current I is established in the wire as shown in the figure, the loop will:

(A) rotate about an axis parallel to the wire

(B) move away from the wire

(C) move towards the wire

(D) remain stationary

3. The resulting magnetic field at the point O due to the current carrying wire shown in the figure:

(A) points out of the page

(B) points into the page

(C) is zero

(D) is the same as due to the segment WX along.

4. A particle enters the region of a uniform magnetic field as shown in figure. The path of the particle inside the field is shown by dark line.

The particle is:

(A) electrically neutral

(B) positively charged

(C) negatively charged

(D) information given is inadequate

5. In the given figure, what is the magnetic field induction at point O?

(A)

(B)

(C)

(D)

6. An electron is revolving around a proton in a circular orbit of diameter 1A°. If it produces a magnetic field of 14 wb/m2 at the proton, then its angular velocity will be about

(A) 8.75 × 1016 rad/s

(B) 1010 rad/s

(C) 4 × 1015 rad/s

(D) 1015 rad/s

7. Electrons at rest are accelerated by a potential of V volt. These electrons enter the region of space having a uniform, perpendicular magnetic induction field B. The radius of the path of the electrons inside the magnetic field is:

(A)

(B)

(C)

(D)

8. Two long parallel wires carry currents i1 and i2 (i1 > i2) when the currents are in opposite direction, the magnetic field at a point midway between the wires is 30 mT. If the direction of i2 is changed, the field becomes 10 mT . The ratio i1/i2 is

(A) 1

(B) 3

(C) 2

(D) 4

9. An infinitely long straight conductor is bent into shape as shown in figure. It carries a current I A. and the radius of circular loop is r metre. Then the magnetic induction at the centre of the circular loop is:

(A) 0

(B) ∞

(C)

(D)

10. A charged particle is released from rest in a region of steady and uniform electric and magnetic fields which are parallel to each other. The particle will move in a

(A) straight line

(B) circle

(C) helix

(D) cycloid

ANSWER:

1. (B)   2. (C)   3. (B)   4. (A)   5. (C)   6. (A)   7. (B)   8. (C)   9. (D)   10.(A)  

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