Summary of HC Verma Solutions Part 2 Chapter 42: Photoelectric Effect And Wave-Particle Duality
FAQs on HC Verma Solutions Class 12 Chapter 42 - Photoelectric Effect and Wave-Particle Duality
1. Where can I find reliable and accurate solutions for all questions in HC Verma's Class 12 Physics Chapter 42?
You can find comprehensive, step-by-step solutions for all exercises in HC Verma's 'Concepts of Physics', Chapter 42 on Photoelectric Effect and Wave-Particle Duality, right here on Vedantu. Our solutions are crafted by subject matter experts to help you understand the correct problem-solving methodology for both objective and subjective questions, aligned with the 2025-26 academic curriculum.
2. What are the key formulas from Chapter 42 that are essential for solving HC Verma's numerical problems?
To successfully solve the problems in this chapter, you must be proficient with the following key formulas:
Einstein's Photoelectric Equation: K_max = hν - Φ₀, where K_max is the maximum kinetic energy, hν is the photon energy, and Φ₀ is the work function.
Energy of a Photon: E = hν = hc/λ, where h is Planck's constant, ν is frequency, c is the speed of light, and λ is the wavelength.
Work Function and Threshold Frequency: Φ₀ = hν₀, where ν₀ is the threshold frequency.
de Broglie Wavelength: λ = h/p = h/mv, where p is the momentum of the particle.
3. How should I apply Einstein's photoelectric equation when solving numericals in HC Verma?
When applying Einstein's photoelectric equation (K_max = hν - Φ₀), follow these steps:
Identify the given values, such as the frequency (ν) or wavelength (λ) of incident light and the work function (Φ₀) or threshold frequency (ν₀) of the metal.
Calculate the energy of the incident photon (E = hν). If wavelength is given, use E = hc/λ.
Ensure all units are consistent (e.g., convert electron volts to Joules if necessary).
Substitute the values into the equation to find the maximum kinetic energy (K_max) of the ejected photoelectrons.
If the problem asks for the stopping potential (V₀), use the relation K_max = eV₀.
4. Why is understanding 'work function' and 'threshold frequency' critical for correctly solving photoelectric effect questions in HC Verma?
Understanding work function (Φ₀) and threshold frequency (ν₀) is critical because they form the basis of the photoelectric effect. The work function is the minimum energy required to eject an electron from a metal surface. No matter how intense the light is, if the energy of its photons (determined by frequency) is less than the work function, no photoemission will occur. This concept is a common trap in HC Verma problems where high-intensity, low-frequency light is used. Correctly identifying if the incident frequency is above the threshold frequency is the first step to solving any such problem.
5. What is a common conceptual error students make when calculating the de Broglie wavelength in HC Verma's problems?
A common error is incorrectly calculating the momentum (p) of the particle. Students sometimes forget that for an electron accelerated through a potential difference (V), its kinetic energy (K) is eV. The relationship between kinetic energy and momentum is K = p²/2m, so p = √(2mK) = √(2meV). Many students incorrectly use formulas for momentum that do not apply to the given situation, leading to wrong calculations for the de Broglie wavelength (λ = h/p). Always determine the particle's momentum based on the information provided, such as its velocity or the potential difference it was accelerated through.
6. How do the solutions in HC Verma Chapter 42 help demonstrate that the kinetic energy of photoelectrons depends on frequency, not intensity?
The problems and solutions in HC Verma's chapter are designed to test this core concept. You will encounter questions where the intensity of light is doubled while the frequency remains constant. The solution will show that while the number of photoelectrons (photocurrent) doubles, the maximum kinetic energy (K_max) and the stopping potential remain unchanged. Conversely, other problems will increase the light's frequency, and the solutions will demonstrate a direct, linear increase in K_max. By working through these specific scenarios, you can solidify your understanding of this fundamental principle of quantum physics.
7. How does the approach to solving 'Objective I' and 'Objective II' questions differ from the 'Exercises' in this chapter?
The approach differs significantly based on the question type. For 'Objective I' (single correct answer) and 'Objective II' (one or more correct answers), your focus should be on quickly identifying the core concept being tested and eliminating incorrect options. These often involve conceptual understanding, such as the relationship between intensity, frequency, and kinetic energy. For the 'Exercises', a detailed, step-by-step calculation is required. You must show the application of formulas like Einstein's equation or the de Broglie relation, manage units carefully, and present a clear, logical solution path.
