The number of atoms in the basis of a primitive cell of hexagonal closed packed structure is:
- 1
- 2
- 3
- 4
The Correct Option is B
Solution and Explanation
In a hexagonal close-packed (hcp) structure, there are two atoms in the basis of a primitive cell. This is because, while the hcp lattice has a total of 6 atoms in a unit cell, when accounting for the fractional contributions of atoms at the edges and corners, the number of atoms in the primitive cell (basis) is reduced to 2.
Therefore, the correct answer is 2.
Top Questions on Modern Physics
- In Photo- electric effect
(A) There is no time interval (very small ~ 10⁻⁹s) between incidence of light and emissions of photo electrons.
(B) Higher the frequency of light, more is the kinetic energy of photo electrons emitted.
(C) A bright light yields more photo-electrons than dim light.
(D) Blue light emits slower electrons than red light.
Choose the correct answer from the options given below:- CUET (PG) - 2025
- Geophysics
- Modern Physics
- X- rays of wavelength 15 pm are scattered from a target. The wavelength of the X-rays scattered through 60° is (Given compton wavelength = 2.426 pm)
- CUET (PG) - 2025
- Geophysics
- Modern Physics
- The Rayleigh Jean's Law,
(A) agrees well with experimental results at low frequencies.
(B) agrees well with experimental results at longer. wavelengths.
(C) shows ultra-violet catastrophe at higher frequencies.
(D) agrees well with experimental results at higher frequencies.
Choose the correct answer from the options given below:- CUET (PG) - 2025
- Geophysics
- Modern Physics
- The energy of a photon is \(6.6 \times 10^{-19} \, \text{J}\). What is the frequency of the photon?
(Take Planck’s constant \(h = 6.6 \times 10^{-34} \, \text{Js}\))- VITEEE - 2025
- Physics
- Modern Physics
- Light of wavelength \( 400\, \text{nm} \) falls on a metal with work function \( \phi = 2.0\, \text{eV} \). If the intensity of the light is doubled, what happens to the maximum kinetic energy of the emitted photoelectrons?
- BITSAT - 2025
- Physics
- Modern Physics
Questions Asked in IIT JAM exam
- The shortest distance between an object and its real image formed by a thin convex lens of focal length 20 cm is _____ cm. (in integer)
- If \(\left(\frac{1-i}{1+i}\right)^{n/2} = -1\), where \(i = \sqrt{-1}\), one possible value of n is
- IIT JAM PHY - 2025
- Complex numbers
- In a two-level atomic system, the excited state is 0.2 eV above the ground state. Considering the Maxwell-Boltzmann distribution, the temperature at which 2% of the atoms will be in the excited state is _____ K. (up to two decimal places)
(Boltzmann constant \(k_B = 8.62 \times 10^{-5}\) eV/K)
- IIT JAM PHY - 2025
- Mechanics
At a particular temperature T, Planck's energy density of black body radiation in terms of frequency is \(\rho_T(\nu) = 8 \times 10^{-18} \text{ J/m}^3 \text{ Hz}^{-1}\) at \(\nu = 3 \times 10^{14}\) Hz. Then Planck's energy density \(\rho_T(\lambda)\) at the corresponding wavelength (\(\lambda\)) has the value \rule{1cm}{0.15mm} \(\times 10^2 \text{ J/m}^4\). (in integer)
[Speed of light \(c = 3 \times 10^8\) m/s]
(Note: The unit for \(\rho_T(\nu)\) in the original problem was given as J/m³, which is dimensionally incorrect for a spectral density. The correct unit J/(m³·Hz) or J·s/m³ is used here for the solution.)- IIT JAM PHY - 2025
- Mechanics
- The ratio of the density of atoms between the (111) and (110) planes in a simple cubic (sc) lattice is ____. (up to two decimal places)
- IIT JAM PHY - 2025
- Solid State Physics, Devices, Electronics