Question

In a fluorescent tube of diameter 4.8 cm , 2.7 × 1018 electrons (with a charge of −e) and 2.4 × 1018 positive ions (with a charge of +e) flow in opposite directions through a cross-sectional each second. What is the current in the tube? The fundamental charge is 1.602 × 10−19 C. Answer in units of A.

Answer 1

Answer: 0.817A

Explanation:

Assuming , that one coulomb per second of negative charge alone flow through a conductor and no positive charges flow. I.e Q=It

It means a current of one A flow in the opposite direction.

This is similar to one coulomb per second of positive charge flowing through and there is no negative charge,

In addition, the one coulomb per second of positive charge flows. This is flowing in the current direction of the previous one. Then, the total current is 2 A. Since 2 coulomb of positive charges flow through one due to real positive charge and another due to the negative charge flowing in opposite direction.The charges cannot cancel each other, because even before the current flow the conductor was neutral.

According to this, the current in the given problem is

[2.7 + 2.4] x 10 ^ 18 * 1.602 x 10^ [-19] C/s

= 0.817 A