Physics MCQs for NEET — Practice Questions with Answers

The de-Broglie wavelength of a particle is given by the formula: $$ ext{wavelength} = rac{h}{ ext{momentum}} $$ For an atom at temperature T, the momentum can be related to the thermal energy as $$ p = rac{mv}{ ext{thermal energy}} $$ The thermal energy is given by $$ rac{3kT}{2} $$ Therefore, the de-Broglie wavelength is $$ ext{wavelength} = rac{h}{ ext{momentum}} = rac{h}{ ext{mv}} rac{1}{ ext{thermal energy}} = rac{h}{ ext{mv}} rac{1}{ ext{(3kT/2)}} = rac{h}{ ext{mv}} rac{1}{ ext{(3kT/2)}} = rac{h}{ ext{sqrt}(3mkT)} $$

$ \lambda = { h \over \sqrt{2meV} } $ v = v_2 - V_1 = 40 -20 = 20v $ = { 6.62 \times 10^{-34} \over \sqrt { 2 \times 9.1 \times 10^{-31} \times 1.6 \times 10^{-19} \times 20}}$ $ = 0.274 \times 19^{-9} $ $ = 2.75 A $

According to de Broglie hypothesis, the wavelength of an electron in the nth Bohr orbit is given by: $$ ext{wavelength} = rac{2 ext{π}r}{n} $$ Here, $r$ is the radius of the nth orbit and $n$ is the principal quantum number. This formula is derived from the quantization condition of angular momentum in Bohr's model of the atom, where $mvr = nrac{h}{2 ext{π}}$. Therefore, the correct option is: $$rac{2 ext{π}r}{n} A^ ext{∘}$$

$ \phi = { hc \over \lambda_0 e } = { 6.62 \times 10^{-34 } \times 3 \times 10^8 \over 5 \times 10^{-7} \times 1.6 \times 10^{-19} }$ = 2.48 eV

$ { \phi_1 \over \phi_2 } = { hf_01 \over hf_02} = { f_01 \over f_03} $ $ \therefore { \phi_1 \over \phi_2 } = {1 \over 3 } $

$ \phi = hf_0 $ $ \therefore \phi \,\alpha f_0 $ $ \therefore {(f_0)_{Na} \over (f_0)_{Fe}} = { \phi _{Na} \over \phi_{Fe} } = { 2.5 \over 5 } = {1 \over 2 } $ = 1:2

$ { 1 \over 2 } mv^2 max = eV = 1.6 \times 10^{-19} \times 200 = 3.2 \times 10^{-17} J $

In quantum mechanics, a particle can be described as a group of harmonic waves. This concept is fundamental to the wave-particle duality of matter, where particles exhibit both wave-like and particle-like properties. The group of waves forms a wave packet that represents the particle, with the superposition of waves leading to a localized wave packet that corresponds to the particle's position.