Wave Optics Part 2

Concept:In a single slit diffraction experiment, the linear width $W$ of the central maximum on a screen at distance $D$ is given by $W = \frac{2 \lambda D}{a}$, where $\lambda$ is the wavelength of light and $a$ is the slit width.Explanation:From the formula, $W$ is directly proportional to $\lambda$ when $a$ is constant ($W \propto \lambda$).So increasing $\lambda$ increases $W$: statement A is true.Decreasing $\lambda$ decreases $W$: statement B is false.Also, $W$ is inversely proportional to $a$ when $\lambda$ is constant ($W \propto 1/a$).Thus decreasing slit width $a$ increases $W$: statement C is true.Increasing $a$ decreases $W$: statement D is false.For brightness: when $\lambda$ decreases (constant $a$), the central maximum becomes narrower.The same amount of energy is now concentrated into a smaller area, so peak brightness increases.Hence statement E is true.Therefore, the true statements are A, C, and E.Answer:Option C: A, C, E only.