The work functions of Caesium $$(\mathrm{Cs})$$, potassium $$(\mathrm{K})$$ and Sodium (Na) are $$2.14 ~\mathrm{eV}, 2.30 ~\mathrm{eV}$$ and $$2.75 ~\mathrm{eV}$$ respectively. If incident electromagnetic radiation has an incident energy of $$2.20 ~\mathrm{eV}$$, which of these photosensitive surfaces may emit photoelectrons?
The minimum wavelength of $$X$$-rays produced by an electron accelerated through a potential difference of $$V$$ volts is proportional to :
A $$12 \mathrm{~V}, 60 \mathrm{~W}$$ lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of $$220 \mathrm{~V}$$. Assuming the transformer to be ideal, what is the current in the primary winding ?
Light travels a distance $$\mathrm{x}$$ in time $$t_{1}$$ in air and $$10 \mathrm{x}$$ in time $$t_{2}$$ in another denser medium. What is the critical angle for this medium?