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#quantum mechanics

37 public questions tagged with this topic.

PHYSICS

A hydrogen atom absorbs a photon of energy 12.75 eV from the ground state. To which energy level does it jump? (Use E_n

Given: A hydrogen atom absorbs a photon of energy 12.75 eV from the ground state. To which energy level does it jump? (Use E_n = -13.6/n² eV ) These values define the system as per NCERT data. Formula: E_1 = -13.6 eV. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: E_n = -13.6 + 12.75 = -0.85 eV . -0.85 = -13.6/n² Rightarrow n² = 16 Rightarrow n = 4 . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Laws of Motion, Work Energy Power, Gravitation and System of Particles, Topic: Newton's laws, work-energy theorem and rotational dynamics.

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PHYSICS

In the Bohr model, how many de Broglie wavelengths fit into the circumference of the n = 5 orbit?

Given: In the Bohr model, how many de Broglie wavelengths fit into the circumference of the n = 5 orbit? Formula: 2π r_n = nlambda. Substitution & Calculation: For n = 5, number of wavelengths = 5. Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Physics Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII, continuing as per NCERT advisory for 2026-27),Topic: Fundamental laws, definitions and applications as per latest NCERT. The section explains governing laws, formulas like μ₀ = 4π.

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PHYSICS

In the Bohr model, how many de Broglie wavelengths fit into the circumference of the n = 6 orbit?

Given: In the Bohr model, how many de Broglie wavelengths fit into the circumference of the n = 6 orbit? Formula: 2π r_n = nlambda. Substitution & Calculation: For n = 6, number of wavelengths = 6. Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.

Ref: NCERT Physics Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII, continuing as per NCERT advisory for 2026-27),Topic: Fundamental laws, definitions and applications as per latest NCERT. The section explains governing laws, formulas like μ₀ = 4π.

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CHEMISTRY

Which orbital designation corresponds to quantum numbers n = 4 and l = 3?

Given: Which orbital designation corresponds to quantum numbers n = 4 and l = 3? These values define the system as per NCERT data. Formula: For n = 4 and l = 3, the subshell is 4f (l = 0: s, l = 1: p, l = 2: d, l = 3: f).. This is standard NCERT relation. Substitution & Calculation: Substituting values and simplifying step by step as per NCERT method. Result: The computed value matches expected outcome and confirms correct choice as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: d and f Block Elements, Topic: Lanthanoid contraction due to poor shielding of 4f orbitals.

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PHYSICS

A particle of mass 2.0 × 10⁻²⁹ kg has a de Broglie wavelength of 1.0 nm . What is its momentum?

Given: A particle of mass 2.0 × 10⁻²⁹ kg has a de Broglie wavelength of 1.0 nm . What is its momentum? These values define the system as per NCERT data. Formula: lambda = h/p Rightarrow p = h/lambda = frac6.63 × 10⁻³⁴¹.0 × 10⁻⁹= 6.63 × 10⁻²⁵ kg m/s .. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10⁻⁵, 236 J kg⁻¹ K⁻¹, CH₃CH₂NH₂ etc. into the formula and simplifying step by step. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Oscillations and Waves, Topic: SHM, wave motion and superposition.

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PHYSICS

A photon has an energy of 4.14 × 10⁻¹⁹ J . What is its frequency? (Take h = 6.63 × 10⁻³⁴ J s )

Given: A photon has an energy of 4.14 × 10⁻¹⁹ J . What is its frequency? (Take h = 6.63 × 10⁻³⁴ J s ) These values define the system as per NCERT data. Formula: Energy of photon E = h v. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: v = E/h = frac4.14 × 10⁻¹⁹⁶.63 × 10⁻³⁴ approx 6.24 × 10¹⁴ Hz . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Oscillations and Waves, Topic: SHM, wave motion and superposition.

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PHYSICS

What does the photoelectric effect demonstrate about the nature of light?

The photoelectric effect shows that light behaves as discrete packets of energy (photons), supporting its particle nature. This follows from NCERT principle where relation explains outcome clearly for students.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Dual Nature of Radiation and Matter, Topic: Photoelectric effect, stopping potential, Kmax = eV₀, work function and photon energy. The section explains definitions, governing laws, formulas like μ₀ = 4π × 10⁻⁷ T·m/A, units and illustrative examples.

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PHYSICS

Which of the following is a key feature of photons that distinguishes them from charged particles?

Photons are electrically neutral and thus not deflected by electric or magnetic fields, unlike charged particles such as electrons. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.

Ref: NCERT Physics Textbook for Class XI and XII, Chapter: Moving Charges and Magnetism and Magnetism and Matter, Topic: Magnetic field due to current loop, solenoid and magnetic dipole moment. Page number should be added only after verification from the.

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