Wave Optics

Step 1: Concept
Light exhibits both wave and particle (quantum) properties.
Step 2: Analysis
Interference, Diffraction, and Polarization are phenomena explained by wave theory.
Step 3: Conclusion
The Photoelectric effect can only be explained by considering light as a stream of particles called photons.
Final Answer: (D)

Step 1: Reaction Analysis
The target reaction is the reverse of the formation reaction of 2 moles of .
Step 2: Law of Thermochemistry
.
Step 3: Calculation
kJ.
Final Answer: (c)

Step 1: For reflected light, minima: , maxima: .

Step 2: Solving gives mm.

Step 1: J.

Step 1: Fringe width .

Step 2: , , .

Step 3: .

Step 1: Photoelectric equation: . Change: .

Step 2: ? Using eV·Å, V ≈ 0.3 V.

Step 1: Convert to sine: . So .

Step 2: Phase difference = . Path difference = .

Step 1: Understanding the Concept:
, .
Step 2: Detailed Explanation:


Step 3: Final Answer:
Ratio of maxima to minima .

Step 1: Understanding the Concept:
For first minima in single slit: .
Step 2: Detailed Explanation:
cm m

Step 3: Final Answer:
Wavelength \AA.

Step 1: Understanding the Concept:
Condition for first minimum in single slit diffraction: .
Step 2: Detailed Explanation:

Step 3: Final Answer:
The slit width is 0.2 mm.

Step 1: Understanding the Concept:
In Young's double slit experiment, the fringe width is given by . The number of fringes visible in a given field of view is inversely proportional to the fringe width, hence inversely proportional to the wavelength.
Step 2: Detailed Explanation:
If fringes are seen with wavelength and fringes with , then:
Step 3: Final Answer:
The number of fringes seen with violet light is 90.

Step 1: Understanding the Concept:
, .
Step 2: Detailed Explanation:
Let , . Then . . Ratio .
Step 3: Final Answer:
The ratio is 34.

Step 1: Understanding the Concept:
Convert cosine to sine: .
Step 2: Detailed Explanation:
Write . Phase difference . Path difference .
Step 3: Final Answer:
The path difference is .

Step 1: Understanding the Concept:
Width of central maximum , where is slit width.
Step 2: Detailed Explanation:
As increases, decreases (narrower). Also, the intensity increases because more light passes through the wider slit.
Step 3: Final Answer:
The central maximum becomes narrower and brighter.

Step 1: Understanding the Concept:
Brewster's law relates the angle of incidence for which reflected light is completely polarized.
Step 2: Detailed Explanation:
According to Brewster's law, when unpolarised light is incident at the polarizing angle ( ), the reflected light is completely plane-polarized.
Step 3: Final Answer:
The ray gets plane polarised.

Step 1: Understanding the Concept:
The distance between the first minima on either side of the central maximum is .
Step 2: Detailed Explanation:
Given mm, cm = m, m.
So, m = mm.
Step 3: Final Answer:
The slit width is mm.

Step 1: Understanding the Concept:
Fringe width .
Step 2: Detailed Explanation:

So changes. Both bright and dark fringes spacing change. Colour changes.
Step 3: Final Answer:
Separation between dark fringes also changes.

Step 1: Understanding the Concept:
Coherent sources have constant phase difference.
Step 2: Detailed Explanation:
Coherent sources emit waves with same frequency, same wavelength, and constant phase difference.
Step 3: Final Answer:
Constant phase difference is required.