$\frac{x}{x+4}$ is the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its (i) third permitted energy level to the second level and (ii) the highest permitted energy level to the second permitted level The value of $x$ will be
Correct Answer: 5
Solution and Explanation
Top JEE Main Physics Questions
- 1 mole of ideal diatomic gas is enclosed in a cylinder piston arrangement having cross-sectional area of piston \(4\,\text{cm}^2\). If gas has only rotational modes and \(P_{atm}=100\ \text{kPa}\), some amount of heat is added to the system as a result piston moves up slowly by \(2.5\,\text{cm}\). If temperature change is \(1.2^\circ C\). Find heat given to gas.
- JEE Main - 2026
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- Thermal Physics
Refer the figure below. \( \mu_1 \) and \( \mu_2 \) are refractive indices of air and lens material respectively. The height of image will be _____ cm.
- JEE Main - 2026
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- Optics and Refraction
In single slit diffraction pattern, the wavelength of light used is \(628\) nm and slit width is \(0.2\) mm. The angular width of central maximum is \(\alpha \times 10^{-2}\) degrees. The value of \(\alpha\) is ____.
- JEE Main - 2026
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- Interference and Diffraction
- If X and Y are the inputs, the given circuit works as _______.
- JEE Main - 2026
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If a body of mass 1 kg falls on the earth from infinity, it attains velocity \( v \) and kinetic energy \( k \) on reaching the surface of the earth. The values of \( v \) and \( k \) respectively are _______.
- JEE Main - 2026
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- Gravitation
Top JEE Main Bohr’s Model for Hydrogen Atom Questions
Given below are two statements:
Statement (I) : The dimensions of Planck’s constant and angular momentum are same.
Statement (II) : In Bohr’s model, electron revolves around the nucleus in those orbits for which angular momentum is an integral multiple of Planck’s constant.
In the light of the above statements, choose the most appropriate answer from the options given below:- JEE Main - 2025
- Physics
- Bohr’s Model for Hydrogen Atom
- In Franck-Hertz experiment, the first dip in the current-voltage graph for hydrogen is observed at 10.2 V. The wavelength of light emitted by hydrogen atom when excited to the first excitation level is _____ nm.
(Given $hc = 1245 \, \text{eV nm}, \, e = 1.6 \times 10^{-19} \, \text{C}$).- JEE Main - 2024
- Physics
- Bohr’s Model for Hydrogen Atom
- According to Bohr's theory, the moment of momentum of an electron revolving in the 4th orbit of a hydrogen atom is:
- JEE Main - 2024
- Physics
- Bohr’s Model for Hydrogen Atom
The threshold frequency of a metal is \(f _0\) When the light of frequency \(2 f _0\) is incident on the metal plate, the maximum velocity of photoelectrons is \(v_1\) When the frequency of incident radiation is increased to \(5 f _0\), the maximum velocity of photoelectrons emitted is \(v_2\) The ratio of \(v_1\) to \(v_2\) is :
- JEE Main - 2023
- Physics
- Bohr’s Model for Hydrogen Atom
An electron of a hydrogen like atom, having \(Z=4\), jumps from \(4^{\text {th }}\) energy state to \(2^{\text {nd }}\) energy state. The energy released in this process, will be :
\((\) Given Rch \(=136 eV )\)
Where \(R =\) Rydberg constant
\(c =\) Speed of light in vacuum
\(h =\) Planck's constant- JEE Main - 2023
- Physics
- Bohr’s Model for Hydrogen Atom
Top JEE Main Questions
- 1 mole of ideal diatomic gas is enclosed in a cylinder piston arrangement having cross-sectional area of piston \(4\,\text{cm}^2\). If gas has only rotational modes and \(P_{atm}=100\ \text{kPa}\), some amount of heat is added to the system as a result piston moves up slowly by \(2.5\,\text{cm}\). If temperature change is \(1.2^\circ C\). Find heat given to gas.
- JEE Main - 2026
- Thermal Physics
- Let $S = \{\theta \in (-2\pi, 2\pi) : \cos\theta + 1 = \sqrt{3} \sin\theta\}$. Then $\sum_{\theta \in S} \theta$ is equal to:
- JEE Main - 2026
- Trigonometry
Refer the figure below. \( \mu_1 \) and \( \mu_2 \) are refractive indices of air and lens material respectively. The height of image will be _____ cm.
- JEE Main - 2026
- Optics and Refraction
In single slit diffraction pattern, the wavelength of light used is \(628\) nm and slit width is \(0.2\) mm. The angular width of central maximum is \(\alpha \times 10^{-2}\) degrees. The value of \(\alpha\) is ____.
- JEE Main - 2026
- Interference and Diffraction
\(t_{100\%}\) is the time required for 100% completion of a reaction, while \(t_{1/2}\) is the time required for 50% completion of the reaction. Which of the following correctly represents the relation between \(t_{100\%}\) and \(t_{1/2}\) for zero order and first order reactions respectively
- JEE Main - 2026
- Zero-order Reactions
Concepts Used:
Atoms
- The smallest unit of matter indivisible by chemical means is known as an atom.
- The fundamental building block of a chemical element.
- The smallest possible unit of an element that still has all the chemical properties of that element.
- An atom is consisting of a nucleus surrounded by one or more shells of electrons.
- Word origin: from the Greek word atomos, which means uncuttable, something that cannot be divided further.
All matter we encounter in everyday life consists of smallest units called atoms – the air we breath consists of a wildly careening crowd of little groups of atoms, my computer’s keyboard of a tangle of atom chains, the metal surface it rests on is a crystal lattice of atoms. All the variety of matter consists of less than hundred species of atoms (in other words: less than a hundred different chemical elements).
Every atom consists of an nucleus surrounded by a cloud of electrons. Nearly all of the atom’s mass is concentrated in its nucleus, while the structure of the electron cloud determines how the atom can bind to other atoms (in other words: its chemical properties). Every chemical element can be defined via a characteristic number of protons in its nucleus. Atoms that have lost some of their usual number of electrons are called ions. Atoms are extremely small (typical diameters are in the region of tenths of a billionth of a metre = 10-10 metres), and to describe their properties and behaviour, one has to resort to quantum theory.