Using Einstein's photoelectric equation, the graphical representation between the kinetic energy (E) of emitted Photoelectrons and the frequency of incident radiation ($\nu$) is show correctly in figure

The force acting on the electron in hydrogen atom (Bohr's theory) is related to the principal quantum number n as

Using Bohr's atomic model, the orbital period of electron in hydrogen atom in the $n^{\text{th}}$ orbit is ($\epsilon_0$=permittivity of free space, h=Planck's constant, m = mass of electron, e = electronic charge)

In a transistor amplifier, a change of 0.2 mA in the base current causes a change of 5 mA in the collector current. If input resistance is $2\ \text{k}\Omega$ and voltage gain is 75, the load resistance used in the circuit is