Value of theta of first minimum

AI Thread Summary
The discussion centers on a homework problem involving a diffraction grating with a wavelength of 580 nm and a slit separation of 0.7 μm. The initial calculations for the angle θ using the formula d sin θ = λ led to an incorrect result of 47°, while the expected answer is 56°. The confusion arose from a misunderstanding of the slit separation value, which was clarified to be 0.7 μm, not 70 μm. Additionally, it was noted that part (a) of the problem pertains to a single slit rather than multiple slits. Accurate interpretation of the parameters is crucial for solving diffraction problems correctly.
desmond iking
Messages
284
Reaction score
2

Homework Statement


A parallel beam of monochromatic light of wavelength 580nm is incidentally normal on a diffraction grating. The separation between successive lines on the grating is 0.7μm as shown in the figure.
please refer to the photo , i am having problem with part (a)


Homework Equations





The Attempt at a Solution


my working is d sin θ = λ
sin θ = λ /d , where d is the separation between slits.. by plug in value of λ = 580x10^-9 and d = 1/ (5000x10^2) , i have my θ = 47 ° , the ans given is 56°
why am i wrong?
 

Attachments

  • IMG_20140912_162943[1].jpg
    IMG_20140912_162943[1].jpg
    50.4 KB · Views: 454
Physics news on Phys.org
Where are you given that value for d?
 
Last edited:
NascentOxygen said:
Where are you given that value for d?

sorry i made a typo.
here's what i mean :
sin θ = λ /d , where d is the separation between slits.. by plug in value of λ = 580x10^-9 and d = 0.7x10^-6 , i have my θ = 47 ° , the ans given is 56°
 
Part a asks about a single slit !
And the distance between slits is NOT 70 micrometer.
 

Thread 'Rolling without slipping on a curved surface'

Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »

Similar threads

How to find the minimum angular resolution?
Replies
3
Views
2K
Slit Width & Single Slit Diffraction
Replies
3
Views
2K
Calculating the Number of Lines for a Diffraction Grating
Replies
3
Views
2K
Question about Intensity in an Interference Pattern
Replies
6
Views
8K
Calculating Wavelength Using Diffraction Grating
Replies
17
Views
3K
Interference vs. diffraction patterns
Replies
2
Views
2K
Rayleigh criterion (two wavelengths) + diffraction grating
Replies
4
Views
4K
Can a Diffraction Pattern be Solved Without Complete Information?
Replies
2
Views
2K
Problem involving interference and medium with index n
Replies
1
Views
1K
Finding order of diffraction given angle and wavelength
Replies
10
Views
2K

Hot Threads

Recent Insights

Back
Top