Neet 2005 PYQ Free Mock Test

A telescope has an objective lens of focal length $200\text{cm}$ and an eye piece with focal length $2\text{cm}$. If this telescope is used to see a $50\text{meter}$ tall building at a distance of $2\text{km}$, what is the height of the image of the building formed by the objective lens?

The ground state energy of hydrogen atom is $-13.6\text{eV}$. What is the potential energy of the electron in this state?

Solid targets of different elements are bombarded by highly energetic electron beams. The frequency ($f$) of the characteristic X-rays emitted from different targets varies with atomic number $Z$ as:

Two infinitely long parallel conducting plates having surface charge densities $+\sigma$ and $-\sigma$ respectively, are separated by a small distance. The medium between the plates is vacuum. If ${\epsilon }_0$ is the dielectric permittivity of vacuum, then the electric field in the region between the plates is:

In a semiconducting material the mobilities of electrons and holes are ${\mu }_e$ and ${\mu }_h$ respectively. Which of the following is true?