In a neon discharge tube 2.9 ×  10¹⁸  Ne+ ions move to the right each second while 1.2 ×  10¹⁸  electrons move to the left per second. Electron charge is 1.6 ×  10⁻¹⁹C.  The current in the discharge tube

Given:

• Ne⁺ ions moving to the right: 2.9 × 10¹⁸ ions/second
• Electrons moving to the left: 1.2 × 10¹⁸ electrons/second
• Charge of an electron (e): 1.6 × 10^-19 C

Calculations:

1. Current due to Ne⁺ ions:

The current (I) is the rate of charge flow. For Ne⁺ ions:

    INe+ = Number of ions × Charge per ion
    INe+ = 2.9 × 1018 × 1.6 × 10-19 C/s
    INe+ = 0.464 A
    

This current flows to the right.

2. Current due to electrons:

Electrons carry a negative charge, so the conventional current due to electrons flows opposite to their direction of movement. For electrons:

    Ie⁻ = Number of electrons × Charge per electron
    Ie⁻ = 1.2 × 1018 × 1.6 × 10-19 C/s
    Ie⁻ = 0.192 A
    

This current flows to the right (opposite to the electron flow).

Net Current:

The total current is the sum of the currents due to Ne⁺ ions and electrons:

    Itotal = INe+ + Ie⁻
    Itotal = 0.464 A + 0.192 A
    Itotal = 0.656 A
    

Therefore, the net current in the discharge tube is 0.66 A towards the right.