A source of coherent light falls on two slits, $P$ and $Q$, separated by $80\,\text{mm}$. The light has a single frequency of $1.5 \times 10^{12}\,\text{Hz}$. Light emerging from the slits is received on a screen that is $4.0\,\text{m}$ from the slits. The screen is parallel to the line joining the slits. An intensity sensor is positioned on the screen at the centre of the interference pattern so that the reading is at a maximum. The intensity sensor is then moved along the screen. The sensor passes through two intensity minima, two intensity maxima and comes to rest at the centre of the third intensity minimum. Which distance does the sensor move through?
- A$4.0\,\text{mm}$
- B$10\,\text{mm}$
- C$25\,\text{mm}$
- D$50\,\text{mm}$