An electron in a TV picture tube is accelerated through a potential difference of 10 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)1.0E+4 eV B)1.6E-18 eV C)1.6E-11 eV D)6.3E+22 eV E)2.6E-15 eV

Question

Quizplus · Accepted Answer

The kinetic energy of the electron can be found using the formula: 
KE = qV
where KE is the kinetic energy, q is the charge of the electron, and V is the potential difference.
The charge of the electron is -1.6 x 10^-19 C and the potential difference is 10,000 V.
Therefore,
KE = -1.6 x 10^-19 C x 10,000 V
KE = -1.6 x 10^-15 J
Converting from joules to electron volts:
KE = (-1.6 x 10^-15 J) / (1.6 x 10^-19 J/eV)
KE = -1.0 x 10^4 eV
Since the kinetic energy cannot be negative (we would interpret it as zero in this context), the magnitude of the answer is 1.0E+4 eV, which is the correct choice.

An Electron in a TV Picture Tube Is Accelerated Through