What is current density ? discusss it

What is current density? Write the vector equation connecting current density J with electric field intensity E for an ohmic conductor.

In an experiment to measure the membrane potential of a living plant cell micro-electrodes are placed inside and outside the cell. The membrane potential is measured to be 120 mV and a current of 1.5 nA flows through the membrane .Assume that the current density in the cell is uniform. The total area of the cell membrane is 2.0 m m^(2) and its thickness is 12 mum . (a) What is the current density in the membrane? (b) What is the resistivity of the membrane ?

What are eddy currents ? Discuss brifly any two applications of eddy currents.

What are eddy currents ? Discuss brifly any two applications of eddy currents.

The current density is defined as the current flowing per unit area of cross section of the conductor. Its direction is

The electric intesity E, current density j and conductivity sigma are related as:

A rectangular block of metal of resistivity p has dimensions d xx 2d xx 3d . A potential difference V is applied between two opposite faces of the block. (a) To which two faces of the block should the potential difference V be applied to give the maximum current density? What is the maximum current density? (b) To which two faces of the block should the potential difference V be applied to give the maximum current? What is this maximum current?

The ratio of current density and electric field is called (A) resistivity (B) conductivity (C) Drift velocity (D) Mobility

What is the drift speed of the conduction electrons in a copper wire with radius r = 900 micrometer when it has a uniform current I = 17mA? Assume that each copper atom contributes one conduction electron to the current and the current density is uniform across the wire's cross section. The density of copper is 9000 kg/m^3 and atomic mass is 63.5u .

What is the current in the circuit shown below?