A coil of ' $n$ ' turns and area ' $A$ ' is suddenly removed from a magnetic field, a charge ' $q$ ' flows through the coil. If resistance of the coil is ' $R$ ' then the magnetic flux density is (in $\mathrm{Wb} / \mathrm{m}^2$ )

I - V characteristics of photodiode for different illumination intensities $\mathrm{I}_1, \mathrm{I}_2, \mathrm{I}_3$ and $\mathrm{I}_4$ are drawn as follows. Then the maximum intensity among them is

A body when projected at an angle ' $\theta$ ' with the horizontal reaches a maximum height ' $H$ '. The time of flight of the body will be ( $\mathrm{g}=$ acceleration due to gravity)

If a source emitting waves of frequency ' $F$ ' moves towards an observer with a velocity $\frac{\mathrm{V}}{3}$ and the observer moves away from the source with a velocity $\frac{\mathrm{V}}{4}$, the apparent frequency as heard by the observer will be ( $\mathrm{V}=$ velocity of sound)