Quite often, connecting wires carrying currents in opposite directions are twisted together in using electrical appliances. Explain how it avoids unwanted magnetic fields.

A telephone cable at a place has four long straight horizontal wires carrying a current of 1.0 A in the same direction east to west. The earth's magnetic field at the place is 0.39 G, and the angle of dip is 35°. The magnetic declination is nearly zero. What are the resultant magnetic fields at points 4.0 cm below the cable ?

Distance between two very long parallel wires is 0.2 m. Electric currents of 4 A in one wire and 6 A in the other wire are passing in the same direction. Find the position of a point on the perpendicular line joining the two wires at which the magnetic field intensity is zero.

As shown in the following figure , the magnetic force is acting in the downward direction on the current - carrying wire placed in the magnetic field . What is the direction of the magnetic field ?

Name the devices which a current carrying conductor and magnetic field are used .

A uniform magnetic field of 1.5 T exists in a cylindrical region of radius10.0 cm, its direction parallel to the axis along east to west. A wire carrying current of 7.0 A in the north to south direction passes through this region. What is the magnitude and direction of the force on the wire if, (a) the wire intersects the axis, (b) the wire is turned from N-S to northeast-northwest direction, (c) the wire in the N-S direction is lowered from the axis by a distance of 6.0 cm?

Figure shows a long straight wire of a circular cross-section (radius a) carrying steady current I. The current I is uniformly distributed across this cross-section. Calculate the magnetic field in the region r a.

What is the direction of the magnetic force acting on a current - carrying wire placed in a magnetic field ?

_____ rule is used to find the direction of induced current in a conducting wire, moving in a magnetic field.

Current passing through two parallel wires A and B are I_(1)andI_(2) respectively, If both the currents flow in the same direction, magnetic field near the midpoint of wire is 10 T. If direction of current I_(2) is reversed magnetic field becomes 30T. I_(1)/I_(2)= _____

Write formula for current carrying wire placed in uniform magnetic field.