Physics questions for NEET

For which one of the following, Bohr model is not valid?

The velocity of a small ball of mass M and density d, when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is d/2, then the viscous force acting on the ball will be:

A uniform rod of length 200 cm and mass 500 g is balanced on a wedge placed at 40 cm mark. A mass of 2 kg is suspended from the rod at 20 cm and another unknown mass 'm' is suspended from the rod at 160 cm mark. Find the value of 'm' such that the rod is in equilibrium. (g = 10 m/s^2)

Twenty seven drops of same size are charged at 200 V each. They combine to form a bigger drop. Calculate the potential of the bigger drop.

A big circular coil of 1000 turns and average radius 10 m is rotating about its horizontal diameter at 2 rad s⁻¹. If the vertical component of earth's magnetic field at that place is 2 × 10⁻⁵ T and electrical resistance of the coil is 12.56 Ω, then the maximum induced current in the coil will be:

A thin biconvex lens of refractive index n₁ = 1.5 with R₁ = R₂ = 20 cm is embedded inside a rectangular block of refractive index n₂ = 1.6 having plane outer faces. What is the equivalent focal length of the combination of lenses (assume that all layers are thin)?

A graph represents the T–V curves of an ideal gas (T is the temperature and V the volume) at three pressures P₁, P₂ and P₃, compared with those of Charles's law represented as dotted lines. The curve for P₁ is the steepest, P₂ is less steep and P₃ is the least steep. Then the correct relation is:

A photon and an electron (mass m) have the same energy E. The ratio (λ_photon/λ_electron) of their de Broglie wavelengths is: (c is the speed of light)