Optics & Wave Phenomena

Matching electromagnetic radiation to standard frequency bands:

• X-rays have frequencies typically between $1 \times 10^{16}$ and $3 \times 10^{21}\,\text{Hz}$ (Matches I).
• Microwaves occupy frequencies from $1 \times 10^9$ to $3 \times 10^{11}\,\text{Hz}$ (Matches II).
• Radiowaves occupy the low frequency band from $5 \times 10^5$ to $10^9\,\text{Hz}$ (Matches IV).
• $\gamma$-rays have the highest frequencies, typically $1 \times 10^{18}$ to $5 \times 10^{22}\,\text{Hz}$ (Matches III).

Correct match: A-I, B-II, C-IV, D-III.

Displacement current is that current which arises due to the time rate of change of electric flux (time-varying electric field) between the plates of a charging capacitor or in free space.
According to Maxwell's formulation:

where $\Phi_E = \int \vec{E} \cdot d\vec{A}$ is the electric flux and $\varepsilon_0$ is the permittivity of free space.

In LASIK eye surgery, an excimer laser is used to precisely ablate microscopic layers of corneal tissue to reshape the cornea.

Excimer lasers operate in the ultraviolet (UV) region of the electromagnetic spectrum (typically at a wavelength of $193\,\text{nm}$).

UV photons possess high energy capable of disrupting chemical bonds without causing thermal damage to adjacent tissues. Hence, option 1 is the correct answer.