$A$ ray of light strikes a glass plate at an angle of $60^o$. If the reflected and refracted rays are perpendicular to each other,the index of refraction of the glass is:

$A$ beam of light propagating in medium $A$ with index of refraction $n(A)$ passes across an interface into medium $B$ with index of refraction $n(B)$. The angle of incidence is greater than the angle of refraction; $v(A)$ and $v(B)$ denote the speed of light in $A$ and $B$. Then which of the following is true?

The wavelength of sodium light in air is $5890 \ \mathring{A}$. The velocity of light in air is $3 \times 10^8 \ m/s$. The wavelength of light in a glass of refractive index $1.6$ would be close to......$\mathring{A}$

Frosted glass is widely used for translucent windows. The region where a transparent adhesive tape is stuck over the frosted glass becomes transparent. The most reasonable explanation for this is:

The phase difference between the incident wave and the reflected wave is $180^o$ when a light ray:

$A$ light ray undergoes refraction from air to water,water to glass,and finally from glass back to air. If the emergent ray is parallel to the incident ray,which of the following relations is correct? ($n_{a}, n_{w}, n_{g}$ represent the refractive indices of air,water,and glass respectively.)