Two wires each carrying a steady current I are shown in four configurations in Column I. Some of the resulting effects are described in Column II. Match the statements in Column I with the statements in Column II and indicate your answer by darkening appr

Question

Two wires each carrying a steady current I are shown in four configurations in Column I. Some of the resulting effects are described in Column II. Match the statements in Column I with the statements in Column II and indicate your answer by darkening appropriate bubbles in the 4 × 4 matrix given in the ORS. [2007]

	Column I		Column II
(A)	Point P is situated midway between the wires.	(p)	The magnetic fields (B) at P due to the currents in the wires are in the same direction.
(B)	Point P is situated at the mid-point of the line joining the centers of the circular wires, which have same radii.	(q)	The magnetic fields (B) at P due to the currents in the wires are in opposite directions.
(C)	Point P is situated at the mid-point of the line joining the centers of the circular wires, which have same radii.	(r)	There is no magnetic field at P.
(D)	Point P is situated at the common center of the wires.	(s)	The wires repel each other.

Smart Achievers · Accepted Answer

(2)

A : q, r

B at P due to upper wire is in downward direction and due to lower wire is in upward direction. Hence, q is correct.

As P is the mid point, the two magnetic fields cancel out each other. Therefore, r is correct.

B : p

B at P due to current in loop A is along the axial line towards right and due to current in loop B is also along the axial line towards right. Hence B and P due to the currents in the wires are in the same direction.

C : q, r

The magnetic field due to current in loop A at P is equal and opposite to the magnetic field due to current in loop B at P.

D : q, s

'B' at P due to current in inner loop is perpendicular to the plane of paper directed vertically upwards.

'B' at P due to current in outer loop is perpendicular to the plane of paper directed vertically downwards.

As the currents are in opposite directions, the wires repel each other. But net force on each wire is zero.

Solution

1 $A : q, s; B : p; C : q, r; D : q, r$

2 $A : q, r; B : p; C : q, r; D : q, s$

3 $A : q, s; B : q, r; C : p; D : q, r$

4 $A : p; B : q, r; C : q, s; D : q, r$

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Solution

1 A:q,s ; B:p ; C:q,r ; D:q,r

2 A:q,r ; B:p ; C:q,r ; D:q,s

3 A:q,s ; B:q,r ; C:p ; D:q,r

4 A:p ; B:q,r ; C:q,s ; D:q,r

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1 $A : q, s; B : p; C : q, r; D : q, r$

2 $A : q, r; B : p; C : q, r; D : q, s$

3 $A : q, s; B : q, r; C : p; D : q, r$

4 $A : p; B : q, r; C : q, s; D : q, r$