Class 12th

Radiation from hydrogen gas excited to first excited state is used for illuminating certain metallic plate. When the same plate is exposed to the radiation from some unknown hydrogen like gas excited to the same level it is found that de-Broglie wavelength of fastest photoelectron has decreased by 2.3 times. It is given that energy corresponding to longest wavelength of Lyman series of the unknown gas is 3 times the ionization energy of hydrogen gas (13.6eV). The work function (in eV) of the metallic plate is ______. [Take (2.3)² = 5.25]

Three capacitors each of capacitance C = 2μF are connected with a battery of emf 30V as shown in the figure. When the switch S is closed, the heat generated in circuit will be n/10 mJ. Find the value of n.

The final product 'A' in the following reaction sequence

Consider the given arrangement. The two slits S₁ and S₂ are illuminated by monochromatic light of wavelength λ. Slits S₃ and S₄ are at separation d₁ = λD/(3d), then ratio of maximum and minimum intensity on the screen will be

A radioactive β –emission. A detector records n β –particles in 2s and by next 2s (accumulatively) it records 1.1 n β –particle. Number of β –particles recorded by detector after a long time, is

The reagent, from the following, which converts benzoic acid to benzaldehyde in one step is

Halogenation of which one of the following will yield m-substituted product with respect to methyl group as a major product?

A ray of light is incident on a slab as shown in figure. The refractive index of medium of slab changes as μ = √(1 + y²). The angle made by ray with x – axis at y = √2 is

Two conducting circular loops of radii R₁ and R₂ are placed in the same plane with their centres coinciding. If R₁ » R₂, the mutual inductance M between them will be directly proportional to: