A spark detector consists of a metal mesh placed at a distance of 5.0 mm5.0 \text{ mm}5.0 mm above a thin wire. A potential difference of 4000 V4000 \text{ V}4000 V is applied between the mesh (at 0 V0 \text{ V}0 V) and the wire (at 4000 V4000 \text{ V}4000 V). An alpha particle passes through the mesh, ionising a neon atom at a point P\text{P}P which lies on the 2000 V2000 \text{ V}2000 V equipotential line, releasing one electron.
The electron and the neon ion (Ne+\text{Ne}^+Ne+) have negligible kinetic energy immediately after ionisation at P\text{P}P. The electron then travels to the wire and the neon ion travels to the mesh.
Assuming that the air between the mesh and the wire has no effect on the motion of either particle, calculate the ratio:
ratio=speed of electron when it reaches the wirespeed of neon ion when it reaches the mesh \text{ratio} = \frac{\text{speed of electron when it reaches the wire}}{\text{speed of neon ion when it reaches the mesh}} ratio=speed of neon ion when it reaches the meshspeed of electron when it reaches the wiremass of neon ion=3.35×10−26 kg\text{mass of neon ion} = 3.35 \times 10^{-26} \text{ kg}mass of neon ion=3.35×10−26 kg mass of electron=9.11×10−31 kg\text{mass of electron} = 9.11 \times 10^{-31} \text{ kg}mass of electron=9.11×10−31 kg
In practice, the gas inside the detector does affect the motion of both the electron and the neon ion. State and explain whether the actual ratio under realistic conditions would be larger or smaller than the value calculated in part (a).
