It's passage based but here goes: Question and explanation (and passage below):
A Geiger counter is an instrument used to detect the products of radioactive decay. It consists of a cylindrical metal chamber containing a low-pressure inert gas and a wire which is connected through a resistor to the cylinder, as shown in the figure below.
Figure 1
Geiger counter
A Geiger counter operates as follows. The cylinder–gas wire assembly acts as a capacitor, setting up a strong electric field between the cylinder and the wire. When a sufficiently energetic particle of ionizing radiation enters the chamber, it ionizes the gas, thus freeing electrons. These electrons are accelerated by the electric field to such an extent that they ionize other atoms of gas. This chain reaction results in a current pulse that is transformed into a voltage pulse by the resistor. If the voltage pulse is large enough the counter will emit a click.
If the electric field within the chamber is 1 × 1010 V/m, and a newly released electron, originally at rest, travels one nanometer before colliding with a gas atom and ionizing it, what is the highest possible value for ionization energy of that atom?
A.
1 × 10–19 eV
B.
0.1 eV
C.
10 eV
Correct Answer
D.
1 × 1019 eV
Explanation:
C. The energy of the released electron would be ΔPE = qV = qEd = (1 e)(1010 V/m)(10–9 m) = 10 eV. If this electron is to ionize a gas atom, then the ionization energy of the gas can be no greater than 10 eV.