Light travels through a glass plate of thickness $t$ and having refractive index $\mu$. If $c$ is the velocity of light in vacuum, the time taken by the light to travel through this thickness of glass is:

$A$ small pin fixed on a table top is viewed from above from a distance of $100 \ cm$. By what distance would the pin appear to be raised if it is viewed from the same point through a $9 \ cm$ thick glass slab held parallel to the table (in $cm$)? The refractive index of glass is $1.5$.

$A$ tiny air bubble in a glass slab $(\mu = 1.5)$ appears from one side to be $6 \, cm$ from the glass surface and from the other side,$4 \, cm$. The thickness of the glass slab is......$cm$

An air bubble in a glass slab $(\mu = 1.5)$ is $5 \, cm$ deep when viewed from one face and $2 \, cm$ deep when viewed from the opposite face. The thickness of the slab is......$cm$

When the same monochromatic ray of light travels through a glass slab and through water,the number of waves in a glass slab of thickness $5 \ cm$ is the same as in a water column of height $6 \ cm$. If the refractive index of glass is $1.56$,then the refractive index of water is:

$A$ printed page is kept pressed by a transparent cube of edge $t$. The refractive index of the cube varies as $\mu(z) = 1 + \frac{z}{t}$, where $z$ is the vertical distance from the bottom of the cube. If viewed from the top, then the printed letters appear to be shifted by an amount