Chemistry Exam  >  Chemistry Questions  >  In a cubic unit cell, the angle between norma... Start Learning for Free
In a cubic unit cell, the angle between normal to the planes (111) and (121) is:
  • a)
    19.47º
  • b)
    18.47º
  • c)
    45º
  • d)
    90º
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
In a cubic unit cell, the angle between normal to the planes (111) and...
cosθ=h1h2+k1k2+l1l2h21+k21+l21−−−−−−−−−√h22+k22+l22−−−−−−−−−√
For the (111) and (121) planes:
cosθ=1+2+11+1+1−−−−−−−√1+4+1−−−−−−−√=43–√6–√=432–√
From this,
θ=
19.47Digree
View all questions of this test
Most Upvoted Answer
In a cubic unit cell, the angle between normal to the planes (111) and...
Cubic Unit Cell and Angle Calculation

Cubic Unit Cell: A cubic unit cell is a type of crystal lattice structure where the unit cell is in the shape of a cube. It has atoms or molecules at each of the eight corners of the cube and one in the center of the cube.

Miller Indices: Miller indices are used to represent crystal planes in a lattice structure. They are written in the form (hkl), where h, k, and l are integers.

Angle Calculation: The angle between two planes in a crystal lattice can be calculated using the formula:

cosθ = (h1h2 + k1k2 + l1l2) / sqrt(h1^2 + k1^2 + l1^2) * sqrt(h2^2 + k2^2 + l2^2)

where h1, k1, l1 and h2, k2, l2 are the Miller indices of the two planes.

Given: The two planes are (111) and (121).

Solution:

h1=1, k1=1, l1=1 (for plane (111))
h2=1, k2=2, l2=1 (for plane (121))

cosθ = (1*1 + 1*2 + 1*1) / sqrt(1^2 + 1^2 + 1^2) * sqrt(1^2 + 2^2 + 1^2)
cosθ = 4 / sqrt(3) * sqrt(6)
cosθ = 4 / 3.464 * 2.449
cosθ = 1.1547

θ = cos^-1(1.1547)
θ = 19.47 degrees

Therefore, the angle between normal to the planes (111) and (121) is 19.47 degrees (option A).
Free Test
Community Answer
In a cubic unit cell, the angle between normal to the planes (111) and...
Explore Courses for Chemistry exam
Question Description
In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer? for Chemistry 2025 is part of Chemistry preparation. The Question and answers have been prepared according to the Chemistry exam syllabus. Information about In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer? covers all topics & solutions for Chemistry 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer?.
Solutions for In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for Chemistry. Download more important topics, notes, lectures and mock test series for Chemistry Exam by signing up for free.
Here you can find the meaning of In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer?, a detailed solution for In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer? has been provided alongside types of In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice In a cubic unit cell, the angle between normal to the planes (111) and (121) is:a)19.47ºb)18.47ºc)45ºd)90ºCorrect answer is option 'A'. Can you explain this answer? tests, examples and also practice Chemistry tests.
Explore Courses for Chemistry exam
Signup to solve all Doubts
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev