NEET UG 2010 — Modern Physics

The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function $5.01 \mathrm{eV}$, when ultraviolet light of $200 \mathrm{~nm}$ falls on it, must be

The mass of a ${ }_3 \mathrm{Li}^7$ nucleus is $0.042 \mathrm{u}$ less than the sum of the masses of all its nucleons. The binding energy per nucleon of ${ }_3 \mathrm{Li}^7$ nucleus is nearly

The energy of a hydrogen atom in the ground state is $-13.6 \mathrm{eV}$. The energy of a $\mathrm{He}^{+}$ion in the first excited state will be

A source $\mathrm{S}_1$ is producing, $10^{15}$ photons/s of wavelength $5000 Å$. Another source $S_2$ is producing $1.02 \times 10^{15}$ photons per second of wavelength $5100 Å$. Then, (power of $\left.S_2\right) /\left(\right.$ power of $S_1$ ) is equal to

To get an output $Y=1$ from the circuit shown below, the input must be  

When monochromatic radiation of intensity $I$ falls on a metal surface, the number of photoelectron and their maximum kinetic energy are $N$ and $T$ respectively. If the intensity of radiation is 2I, the number of emitted electrons and their maximum kinetic energy are respectively

The following figure shows a logic gate circuit with two inputs $A$ and $B$ and the output $Y$. The voltage waveforms of $A, B$ and $Y$ are as given   The logic gate is

Which one of the following statement is false?

The device that can act as a complete electronic circuit is

The electron in the hydrogen atom jumps from excited state $(n=3)$ to its ground state $(n=1)$ and the photons thus emitted irradiate a photosensitive material. If the work function of the material is $5.1 \mathrm{eV}$, the stopping potential is estimated to be (the energy of the electron in $n$th state $\mathrm{E}_{\mathrm{n}}=-\frac{13.6}{\mathrm{n}^2} \mathrm{eV}$ )

The activity of a radioactive sample is measured as $\mathrm{N}_0$ counts per minute at $\mathrm{t}=0$ and $\mathrm{N}_0 / \mathrm{e}$ counts per minute at $\mathrm{t}=5 \mathrm{~min}$. The time (in minute) at which the activity reduces to half its value is

The binding energy per nucleon in deuterium and helium nuclei are $1.1 \mathrm{MeV}$ and $7.0 \mathrm{MeV}$, respectively. When two deuterium nuclei fuse to form a helium nucleus the energy released in the fusion is

The decay constant of a radio isotope is $\lambda$. If $A_1$ and $\mathrm{A}_2$ are its activities at times $\mathrm{t}_1$ and $\mathrm{t}_2$ respectively, the number of nuclei which have decayed during the time $\left(\mathrm{t}_1-\mathrm{t}_2\right)$

A beam of cathode rays is subjected to crossed Electric ( $E$ ) and Magnetic fields $(B)$. The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by (where $V$ is the potential difference between cathod and anode)