List of top Questions asked in UP Board XII

Mention the major drawbacks of Rutherford's atomic model.
Temperature of a pure semiconductor is $0\ \mathrm{K$. Comment on its conductivity.}
In a single-slit diffraction pattern, the angle of diffraction for the second minimum is $60^\circ$. Find the width of the slit in terms of $\lambda$.
Four capacitors of equal capacity are connected in series with a battery of 20 V. The middle point O is earthed. Calculate the potential at points P and Q. \includegraphics[width=0.5\linewidth]{image3.png}
State and prove Ampere's circuital law.
Explain the meaning of polarisation of light and show the difference between polarised and unpolarised light with the help of a suitable diagram.
Draw a circuit diagram to obtain characteristic curve in forward bias of p-n junction diode. Mention the effect of forward bias on depletion layer of the junction.
Write the unit of electric flux.
Define electromotive force of a cell.
Self-inductance of a coil is 6 mH and the rate of flow of current in it is $10^3$ A/s. Find the induced emf produced in the coil.
To measure potential difference from a galvanometer, we connect in it:
In electromagnetic waves, phase difference between electric and magnetic field vectors is:
Prism angle of a prism is $A$ and angle of minimum deviation is equal to prism angle. Refractive index of the material of prism will be:
The unit of magnetic dipole moment is
Threshold wavelength for a metal surface is 2000 \AA. On incidence of radiation of 1000 \AA, the kinetic energy of emitted photoelectrons will be
Charge on a piece of metal is \(-3.2\) coulomb. Number of excess electrons in the metal is:
Explain the working method of a reverse biased (p-n) junction diode by making its circuit diagram and explain avalanche breakdown with the help of its V-I characteristic graph.
What is the rectifying process? Explain the half-wave rectifying action of a (p-n) junction diode with the help of a circuit diagram.
Describe briefly Rutherford's \(\alpha\)-particle scattering experiment. What are the shortcomings of this model? How are they rectified in Bohr's model?
What is the difference between nuclear fusion and nuclear fission? Find the value of the energy \( Q \) released with the help of the given nuclear fusion reaction:
\[ \text{1} \, ^1\text{H}_2 + \, ^1\text{H}_3 \rightarrow \, ^2\text{He}_4 + \, ^1\text{n}^1 + Q \] Given:
Mass of \( ^1\text{H}_2 = 2.0141 \, \text{amu} \)
Mass of \( ^1\text{H}_3 = 3.0160 \, \text{amu} \)
Mass of \( ^2\text{He}_4 = 4.0026 \, \text{amu} \)
Mass of \( ^1\text{n}^1 = 1.0087 \, \text{amu} \)
1 amu = 931 MeV
Write the formula of refraction of light through a single spherical surface. The radius of curvature of one end of a cylindrical glass (n = 1.5) rod is 2 cm. Find the position and nature of the image of the point source S. See the figure and also draw the ray diagram.
\includegraphics[width=0.5\linewidth]{image9.png}
Write down the formula for the distances of nth bright and nth dark fringes, from the central fringe in Young's double slit experiment. A monochromatic source of light with wavelength 480 nm, is used in this experiment, in which distance between the double slits is 3 mm. Distance between the slits and screen is 2 m. Find the distance between the 8th bright and the 3rd dark fringes.
What is the working principle of a transformer? The ratio of the number of turns in the primary and secondary coils in an ideal step-down transformer is 20 : 1. When input voltage of 250 V is applied, then the output current is 8 A. Calculate:
i) Current in the primary coil
ii) Output power
Write down Einstein's photoelectric equation. Explain with the help of this equation that what is the effect on the maximum kinetic energy of the emitted electrons, if frequency of the incident light (photons) is increased by \( n \) times. What is the relationship between the work function of the metal surface and threshold wavelength?
Explain the principle of Wheatstone's bridge by Kirchhoff's law. In the given circuit, there is no deflection in the galvanometer \( G \). What is the current flowing through the cell?
\includegraphics[width=0.5\linewidth]{image57.png}