List of top Questions asked in UP Board XII

A coil of area $5 \, \text{cm}^2$ is placed in a uniform magnetic field of $1.5 \, \text{m}$. If the coil has 100 turns and $0.2 \, \text{A}$ of current is passed in it, then find:

Magnetic dipole moment of the coil
Maximum torque on the coil

The radius of nucleus is expressed as $R = R_0 A^{1/3}$, where $A$ is mass number and $R_0 = 1.2 \times 10^{-15} \, \text{m}$. Prove that the density of nucleus does not depend upon the mass number $A$.

With the help of symbol diagram of AND gate, prepare its truth table.

The length of a wire of $10 \, \Omega$ resistance is three times the length on stretching it. Now the wire is cut into three equal parts and then they are joined in an electrical circuit as shown in the figure. Find out the total resistance of the combination between A and B.

Prove that the period of revolution (T) of electrons in stable orbits of the atom is directly proportional to the cube of the principal quantum number ($n$), on the basis of Bohr’s atom model.

The first minima for the wavelength $\lambda_1 = 660 \, \text{nm}$ coincides with the first maxima of some other wavelength $\lambda_2$, in the single-slit diffraction experiment of light. Find out the value of wavelength $\lambda_2$.

Work function of silver is $4.7 \, \text{eV}$. When ultraviolet light of wavelength $100 \, \text{nm}$ is incident on it, the stopping potential obtained is $7.7 \, \text{V}$. Find out the value of the stopping potential for the wavelength of light of $200 \, \text{nm}$.

The drift velocity of free electrons is $v$ on passing current $i$ in a conducting wire. Drift velocity of electrons in the same wire having twice the radius and current $2i$ will be:

The refracting angle of three prisms is $15^\circ$, but their refractive indices are 1.6, 1.5, and 1.4 respectively. If angles of deviation produced by them are $\delta_1, \delta_2,$ and $\delta_3$ respectively, then:

If actual angle of dip is $\theta$ and $\theta'$ is the angle of dip in a plane at an angle $\alpha$ from the magnetic meridian, then $\dfrac{\tan \theta'}{\tan \theta}$ is

If the magnification of objective and eyepiece lenses of a compound microscope are $m_1$ and $m_2$ respectively, then write down the formula for the magnifying power of the microscope.

What is meant by shunt?

What is Kirchhoff’s First Law for the electrical circuit?

Define coefficient of self-induction.

A particle of mass $m$ moves with a speed $v$. Write down the formula of the corresponding de Broglie wavelength of the particle.

In the figure, currents are flowing in opposite directions in two parallel conductors. What should be the current \( I \) in the conductor X, so that the resultant magnetic field at the point P is zero? Current in the conductor Y is 10 ampere.

Explain the nuclear fusion process. What is its example in nature? If 4 neutrons and 3 protons are fused to form lithium \( {}_3^7 \text{Li} \) nucleus, then how much energy (in MeV) will be released?

Explain the working process of the amplifying action of an n-p-n transistor in common emitter configuration by making a circuit diagram and obtain the formula for voltage amplification.

Explain the working process of a forward biased p-n junction diode with the help of a circuit diagram. Show the dynamic resistance by making a graph between the forward voltage and forward current.

Following are the resistances of the four sides of a Wheatstone bridge: AB = 100 \( \Omega \), BC = 10 \( \Omega \), CD = 5 \( \Omega \), DA = 60 \( \Omega \); resistance of galvanometer \( G = 15 \Omega \). Find the value of the current \( i_g \).

Calculate the stored charge and potential difference between the plates in steady state for both the capacitors as shown in the circuit:

In an A.C. circuit, potential difference and current are given as, \[ V = 100 \sin(100t) \, \text{volts}, \quad i = 100 \sin\left(100t + \frac{\pi}{3}\right) \, \text{mA}. \] The power consumed in the circuit is:

The isotones pair of the following are:

The amplitude of the magnetic field in an electromagnetic wave is $3 \times 10^{-10}$ T. If frequency of the wave is $10^{12}$ Hz, then the amplitude of the associated electric field is:

Derive the formula for the magnetic field at a point due to a current-carrying straight long conductor with the help of Ampere’s circuital law.