The wires leading to and from a 0.12-mm-diameter lightbulb filament are 1.5 mm in diameter. The wire to the filament carries a current with a current density of 4.6×105 A/m2 . What is the current in the filament? Express your answer to two significant figures and include the appropriate units.

The current in the filament is 0.81 A

Explanation:

Given :

Diameter of wire m

Diameter of filament m

Current density

From the formula of current density,

Where area =

Current in the filament is given by,

Area of filament is given by

Put value of A in above equation,

  A

Therefore, current in the filament is 0.81 A

option number c is the right answer.