List of top Physics Questions asked in UP Board XII

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 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.

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.

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.

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?

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:

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.

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.

The isotones pair of the following are:

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.

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 \( i_g \).

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

Define 1 ampere on the basis of the force acting between two parallel current-carrying conductors.

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.

Two biconcave lenses of glass (\( n_g = \frac{3}{2} \)) of radius of curvature 10 cm are placed in contact. Water (\( n_w = \frac{4}{3} \)) is filled in between the lenses. Find the power and nature of the combined lens.

What is diffraction of light? Find the formula for the angular fringe width of the central maxima obtained in the diffraction pattern of monochromatic light by a single slit. Show the diagram of intensity distribution of light in the diffraction pattern.

Distance of the second dark fringe from the central maxima on the screen for \( 6000 \, \text{Å} \) wavelength.