List of top Questions asked in UP Board XII

Write down the formula for the electric potential on the axial line of an electric dipole.

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 $200 \, \text{nm}$.

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 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:

What is meant by shunt?

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

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 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.

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

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.

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 \( i_g \).

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:

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?

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:

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.

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.

Derive the formula for the electric field due to a uniformly charged straight wire of infinite length by using Gauss' law.

As shown in the figure, a ray of light is incident at an angle of \( 45^\circ \) at the surface AB of the transparent slab. Find the value of the minimum refractive index \( n \) of the slab, when there is total internal reflection of the light ray at the vertical face BC.