The strip on the back of a credit card/debit card is a magnetic strip, often called a _____.

Banks ask our PAN/Credit card/ dibit card number on mobile phones.

A currrent I is passed through a silver strip of width d and area of cross section A. The number of free electrons per unit volume is n. (a) Find the drift velocity v of the electrons. (b) If a magnetic field B exists in the region as shown in what is the average magnetic force on the free electrons? (c) Due to the magnetic force, the free electrons get accumulated on one side of the conductor along its length. This produces a transverse electric field in the conductor which opposes the magnetic force on the electrons. Find the magnitude of the electric field which will be the potential diference developed across the width of the conductor due to the electron- accumulation? The appearance of a transverse emf, when a current-carrying wire is placed in a magnetic field, is called hall effect.

Two metal strips, each of length, each of length l, are clamped parallel to each other on a horizontal floor with a separation b between them. A wire of mass m line on them perpendicularly as shown in figure. A vertically upward magnetic field of strenght B exists in the space. The matal strips are smooth but the cofficient of freiction between the wire and the floor is mu . A current i is established when the switch S is closed at the instant t=0 . Discuss the motion of the wire after the switch is closed. How far away from the strips will the wire reach?

Figure shows a cross section of a large metal. Sheet carrying an electric current along its surface. The current in a strip of width dl is Kdl where K is a constant. Find the magnetic field at a point P at a distance x from the metal sheet.

Two large metal sheets carry surface currents as shown in figure . The current through a strip of width dl is Kdl where K is a constant . Find the magnetic field at the points P,Q and R.

The cells of endodermis show band like thickening on their radial and inner tangential walls called casparian strips. Why?