The wavelength of light from the spectral emission line of sodium is 589 nm. Find the kinetic energy at which
(a) an electron, and
(b) a neutron, would have the same de Broglie wavelength.
Wavelength of light of a sodium line, λ = 589 nm = 589 × 10−9 m
Mass of an electron, me= 9.1 × 10−31 kg
Mass of a neutron, mn= 1.66 × 10−27 kg
Planck’s constant, h = 6.6 × 10−34 Js
(a) For the kinetic energy K, of an electron accelerating with a velocity v, we have the relation:
K = 1/2 mev2 ..... (1)
We have the relation for de Broglie wavelength as:
Substituting equation (2) in equation (1), we get the relation:
Hence, the kinetic energy of the electron is 6.9 × 10−25 J or 4.31 μeV.
(b) Using equation (3), we can write the relation for the kinetic energy of the neutron as:
Hence, the kinetic energy of the neutron is 3.78 × 10−28 J or 2.36 neV.
NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:
This question is important because it tests key concepts from the NCERT syllabus and is frequently asked in CBSE exams.
This question is based on core NCERT concepts explained in the chapter and should be revised thoroughly before exams.
Wavelength of light of a sodium line, λ = 589 nm = 589 × 10−9 m
Mass of an electron, me= 9.1 × 10−31 kg
Mass of a neutron, mn= 1.66 × 10−27 kg
Planck’s constant, ...
Step-by-step explanation:
• Wavelength of light of a sodium line, λ = 589 nm = 589 × 10−9 m
•
• Mass of an electron, me= 9
• 1 × 10−31 kg
•
Students often lose marks by skipping steps, writing incomplete explanations, or misunderstanding keywords used in the question.
Stay updated with our latest educational content and study tips
Voice is a crucial aspect of English grammar. It indicates if the subject of the sentence is performing the action or if the action is performed on the subject. To know the difference between the active and passive voice, contributing to the improvement of writing, speaking, and sentence clarity. In this article, you will learn … Read more
Read More
Have you ever noticed that doing activities such as playing outdoors, chilling with your friends, or using the mobile phone feels so effortless and fun? Whenever you might have played sports, you kept on playing even when it felt hard initially just so you could get that feeling after the game, a feeling of accomplishment, … Read more
Read More
Imagine this; You’re sitting in the test hall, pen in hand, and the question paper has been put in front of you. Rather than freezing, you feel calm, collected, and set. Why? As you have formerly been there in your mind. You’ve seen yourself sitting composibly, reviewing the question paper fluently, performing well in the … Read more
Read More
Parent-Teacher Meetings (PTMs) are more than quick updates on marks — they’re a chance to build a real partnership between home and school. A good Parent-Teacher Meeting conversation helps parents see beyond grades. It opens up insights about a child’s strengths, struggles, emotions and even hidden talents. When parents participate actively, they don’t just track … Read more
Read More
Student Discussion
Be the first to comment.
ADD NEW COMMENT