Mu Lambda Relationship

Q.

A plane glass slab is kept over various coloured letters, the letter which appears least raised is?

1. Blue

2. Green

3. Red

4. Violet

Q. Monochromatic light of wavelength 589 nm is incident from air on awater surface. What are the wavelength, frequency and speed of(a) reflected, and (b) refracted light? Refractive index of water is1.33.

Q. In $YDSE$, the thickness of a glass slab $(\mu =1.5)$ which should be placed in front of the upper slit $S_1$ so that the central maximum now lies at a point where the $5^{th}$ bright fringe was lying earlier (before inserting the slab), is given by $x\times {10}^4\dot{\text{A}}$. The value of $x$ is (Integer only)
[Wavelength of light $=5000\dot{\text{A}}$]

Q. An electromagnetic wave of frequency $3\text{GHz}$ enters a dielectric medium of relative electric permittivity $2.25$ from vacuum. The wavelength of this wave in that medium will be $\times {10}^{-2}\text{cm}$.