The SI unit is named in honour of Lord Kelvin - Leaving Cert Physics - Question 11 - 2008

The newton (N) is the force that gives a mass of 1 kg an acceleration of 1 m/s², expressed mathematically as: $F = ma$.

The change in momentum (Δp) can be calculated using the formula:

Given the force is 9 kN and time is 0.6 ms:

1. X-rays
2. Microwaves
3. Ultra-violet rays

The photoelectric effect is the emission of electrons from a metal surface when it is exposed to light or radiation of a suitable frequency.

The quantum theory of light was revolutionary because it proposed that light travels in discrete packets of energy called photons, indicating that light has both particle and wave properties. This contradicted classical wave theory.

The energy (E) of a photon can be calculated using the formula: $E = hf$ where h is Planck's constant and f is the frequency. Plugging in the values: $E = (6.63 imes 10^{-34} ext{ J s}) (3.3 imes 10^{14} ext{ Hz}) = 2.18 imes 10^{-19} ext{ J}.$

The loss of mass can be calculated using Einstein's equation: $E = mc^2$ Rearranging gives: $m = \frac{E}{c^2}$ Substituting the given energy (E = 100 MJ = 1 imes 10^8 J) and the speed of light (c = 3 imes 10^8 m/s): $m = \frac{1 imes 10^8}{(3 imes 10^8)^2} = \frac{1 imes 10^8}{9 \times 10^{16}} \approx 1.11 \times 10^{-9} ext{ kg}.$