Physics Modern Physics questions from NEET UG 2005.
Application of a forward bias to a $p-n$ junction:
Carbon, silicon and germanium atoms have four valence electrons each. Their valence and conduction bands are separated energy band gaps represented $\left(E_g\right)_C,\left(E_g\right)_{S i}$, and $\left(E_g\right)_{G e}$ respectively. Which one of the following relationship is true in their case?
Choose the only false statement from the following:
Energy levels $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$ of a certain action corresponding to increasing values of energy i.e. $E_A < E_B < E_C$. If $\lambda_1$, $\lambda_2$ and $\lambda_3$ are wavelength of radiations corresponding to transitions $\mathrm{C}$ to $\mathrm{B}, \mathrm{B}$ to $\mathrm{A}$ and $\mathrm{C}$ to $\mathrm{A}$ respectively, which of the following relations is correct?
Fission of nuclei is possible because the binding energy per nucleon in them:
In any fission process the ratio: mass of fission products mass of parent nucleus is:
In the reaction ${ }_1^2 \mathrm{H}+{ }_1^3 \mathrm{H} \rightarrow{ }_2^4 \mathrm{He}+{ }_0^1 n$, if the binding energies of ${ }_1^2 \mathrm{H},{ }_1^3 \mathrm{H}$ and ${ }_2^4 \mathrm{He}$ are respectively $a, b$ and $c$ (in Me V), then the energy (in $\mathrm{MeV}$ ) released in this reaction is:
The nuclei of which one of the following pairs of nuclei are isotones?
The photosensitive metallic surface has work function $h v_0$ fall on this surface, the electrons come out with a maximum velocity of $4 \times 10^6 \mathrm{~m} / \mathrm{s}$. When the photon energy is increased $5 h v_0$. Then maximum velocity of photoelectrons will be:
The total energy of an electron in the first excited state of hydrogen atom is about $-3.4 \mathrm{eV}$. Its kinetic energy in this state is:
The work functions for metal $\mathrm{a}, \mathrm{b}$ and c are respectively $1.92 \mathrm{eV}, 2.0 \mathrm{eV}$ and 5 eV. According to Einstein's equation the metals which will emit photoelectrons for a radiation of wavelength $4100 Å$ is a/are:
Zener diode is used for: