An electron in a TV picture tube is accelerated through a potential difference of 20 kV before it hits the screen.What is the kinetic energy of the electron in electron volts? (1 eV = 1.6 × 10−¹⁹ J) A) 6.25 × 10²² eV B) 1.0 × 10⁴ eV C) 2.0 × 10⁴ eV D) 3.2 × 10−²² eV

Question

Quizplus · Accepted Answer

The kinetic energy of an electron can be calculated using the formula:
Kinetic Energy = qV
where q is the charge of the electron and V is the potential difference.
The charge of an electron is -1.6 × 10^-19 C, and the potential difference in this case is 20 kV, which is equivalent to 20,000 V.
Therefore, the kinetic energy of the electron is:
Kinetic Energy = -1.6 × 10^-19 C × 20,000 V
Kinetic Energy = -3.2 × 10^-15 J
To convert this to electron volts (eV), we divide by the conversion factor of 1.6 × 10^-19 J/eV:
Kinetic Energy = (-3.2 × 10^-15 J) / (1.6 × 10^-19 J/eV)
Kinetic Energy = -20 eV
Since kinetic energy cannot be negative, we take the absolute value:
Kinetic Energy = 20 eV
Therefore, the correct answer is choice C: 2.0 × 10^4 eV.

An Electron in a TV Picture Tube Is Accelerated Through