An alternating voltage $\mathrm{E}=100 \sqrt{2} \sin (50 \mathrm{t})$ is connected to a $2 \mu \mathrm{~F}$ capacitor through an a.c. ammeter. The ammeter reading will be

In a Fraunhoffer diffraction, light of wavelength ' $\lambda$ ' is incident on slit of width ' d '. The diffraction pattern is observed on a screen placed at a distance ' $D$ '. The linear width of central maximum is equal to two times the width of the slit, then 'D' has value

When a big drop of water is formed from ' $n$ ' small drops of water, the energy loss is ' 3 E ' where ' $E$ ' is the energy of the bigger drop. The radius of the bigger drop is ' R ' and that of smaller drop is ' $r$ ' then the value of ' $n$ ' is

The ratio of the wavelength of the last line of Paschen series to that of Balmer series is