List of top Physics Questions on Modern Physics asked in UP Board XII

Mention the required conditions for the interference of light. In Young's double slit experiment, the intensity of light at a point on the screen is \( I \), when path difference is \( \lambda \) by using monochromatic light of wavelength \( \lambda \). Find the intensity of light at that point, where path difference is \( \frac{\lambda}{4} \).
Obtain the formula for the intensity of electric field outside a charged thin spherical shell with the help of Gauss' law.
n electric dipoles are placed inside a closed surface. Total electric flux linked with the closed surface will be:
The unit of coefficient of self-inductance is:
What is Brewster's law?
The length of the image formed by a concave mirror:
Write down the formula for refraction of light from a spherical surface and with the help of this, derive the relation \( \frac{1}{f} = (n - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right) \) for a thin lens. Also show that, the focal length for concave lens will be negative.
Which nature of light is supported by Young’s double slit experiment? The light used in Young’s double slit experiment contains two wavelengths, 6000 \AA\ and 5000 \AA. Separation between the slits is \(10^{-3}\) m and the screen is at a distance of 1 m from the slits. Find minimum distance from the central maxima where bright fringes for both the wavelengths are coincident.
Derive the formula for the capacitance of a parallel plate capacitor partially filled with a dielectric medium between the plates.
State Huygens' principle of secondary wavelets. With the help of this principle, explain the laws of reflection of light.
Give pictorial representation of polarized and unpolarised light. Polarizing angle for a transparent medium is 60°. Find the value of angle of refraction and refractive index of the medium.
What is an astronomical telescope? Draw ray diagram for an astronomical telescope when final image is formed at infinity.
Do two equipotential surfaces intersect each other? Answer with reason.
What is the meaning of electrical capacity of a conductor? Find the unit of the electrical capacity of the conductor.
Resistivity of a conducting wire depends on:
Which nature of light is supported by the phenomenon of photoelectric effect? Write Einstein's equation related to photoelectric emission and briefly explain the laws of photoelectric emission on its basis.
What is an electrical capacitor? Find the expression for the capacity of a parallel plate capacitor. On which factors does the capacitance depend?
Derive Lens Maker's formula for a thin lens. Mention the effect of the refractive index and radius of curvature of the curved surfaces on the focal length of the lens.
Define drift velocity and mobility of electrons in a metallic conductor. The length of a conducting rod is 1 m and the potential difference between its ends is 4 volt. Electron density in the conductor is \( 5 \times 10^{24}~\text{m}^{-3} \) and its resistivity is \( 50 \times 10^{-8}~\Omega\)-m. Calculate the drift velocity of the electrons in the metal.
Explain the meaning of polarisation of light and show the difference between polarised and unpolarised light with the help of a suitable diagram.
To measure potential difference from a galvanometer, we connect in it:
Threshold wavelength for a metal surface is 2000 \AA. On incidence of radiation of 1000 \AA, the kinetic energy of emitted photoelectrons will be
Define energy band in solids.
Who discovered the photoelectric effect?
A proton (p) and an $\alpha$-particle are accelerated to the same potential difference. Find the ratio of de Broglie wavelengths associated with proton and $\alpha$-particle.