Two free parallel wires carrying currents in opposite direction [CPMT 1977; MP PMT 1993; AFMC 2002; CPMT 2003]
Two wires, if carries current in opposite direction, they repel each other.
A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current I is established in wire as shown in figure, the loop will
[IIT 1985; MP PET 1995; MP PMT 1995, 99; AIIMS 2003]
A circular coil of radius 4 cm and of 20 turns carries a current of 3 amperes. It is placed in a magnetic field of intensity of 0.5 weber/m2. The magnetic dipole moment of the coil is [MP PMT 2001]
A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field B−→, such that B−→ is perpendicular to the plane of the loop. The magnetic force acting on the loop is [BIT 1992; MP PET 1994; IIT 1983; MP PMT 1999; AMU (Engg.) 2000]
Net force on a current carrying closed loop is always zero, if it is placed in an uniform magnetic field.
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 [CPMT 1991; IIT 1986; Bihar MEE 1995; RPMT 1997; MP PET 1996; MP PMT 1994, 96, 99; UPSEAT 2001, 03]
Through two parallel wires A and B, 10 and 2 ampere of currents are passed respectively in opposite direction. If the wire A is infinitely long and the length of the wire B is 2 m, the force on the conductor B, which is situated at 10 cm distance from A will be [CPMT 1988; MP PMT 1994]
If two streams of protons move parallel to each other in the same direction, then they [MP PET 1999; AIIMS 2004]
For charge particles, if they are moving freely in space, electrostatic force is dominant over magnetic force between them. Hence due to electric force they repel each other.
Two long and parallel wires are at a distance of 0.1 m and a current of 5 A is flowing in each of these wires. The force per unit length due to these wires will be [CPMT 1977]
Two straight parallel wires, both carrying 10 ampere in the same direction attract each other with a force of 1×10−3N. If both currents are doubled, the force of attraction will be [MP PET 1994]
A circular coil of radius 4 cm has 50 turns. In this coil a current of 2 A is flowing. It is placed in a magnetic field of 0.1 weber/m2. The amount of work done in rotating it through 180° from its equilibrium position will be [CPMT 1977]
3 A of current is flowing in a linear conductor having a length of 40 cm. The conductor is placed in a magnetic field of strength 500 gauss and makes an angle of 30∘ with the direction of the field. It experiences a force of magnitude [MP PET 1993]
A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon [CPMT 1985; RPMT 1997; Kerala PMT 2002]
To make the field radial in a moving coil galvanometer [MP PET 1993]
The deflection in a moving coil galvanometer is [MP PMT 1993]
In a moving coil galvanometer, the deflection of the coil θ is related to the electrical current i by the relation [MP PMT 1996, 2000, 03; RPMT 1997; CPMT 1975; MP PET 1999]