# Giancoli: Wave Nature of Light: Parallel Crests 2.5cm Apart

• leolaw
In summary, the question is asking for the angle at which there would be little or no wave action when parallel water waves with 2.5cm apart crests pass through two openings that are 5cm apart in a board. The provided distance of 2.0m beyond the board is not necessary in solving for the angle, as long as it is much greater than a wavelength. The angle can be found using the equation d sin(\theta) = (m + \frac{1}{2})(0.025m) where d is 0.05m and m is 0.
leolaw
This question is related to the wave nature of light from Giancoli:

Water waves having parallel crests 2.5cm apart pass through two openings 5cm apart in a board. At a point 2.0m beyond the board, at what angle relative to the "straight-through" direction would there be little or no wave action?

The reason I am having a problem with this question is because I cannot visualize what a "parallel crest watever wave" is. Is it like the one in this picture (http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/imgpho/sinslitwid.gif) ?

Yes, those are paralllel crests.

how can i find the wavelength of the water wave?
Is it simply just 1/2.5cm or 40m?

Last edited:
what's the definition of wavelength?

distance from crust to crust, gottcha

I find the angle to be 14.48 degree, but I didn't use the 2 meters that the question provdied. Am I missing something?

I use $$d sin (\theta) = (m + \frac {1}{2} )(0.025m)$$ where d = 0.05m, and m = 0 to find $$\theta$$.

Last edited:
leolaw said:
I find the angle to be 14.48 degree, but I didn't use the 2 meters that the question provdied. Am I missing something?

I use $$d sin (\theta) = (m + \frac {1}{2} )(0.025m)$$ where d = 0.05m, and m = 0 to find $$\theta$$.

Since the problem asked you for the angle, and not a distance from the midpoint, you do not need the 2m as long as that distance is much greater than a wavelength. If the distance were only a couple of wavelengths, the approximations used to derive the equation you used would not be justified. Look carefully at this diagram and you will see that there are two angles $\theta$ and $\theta^\prime$ that are only approximately equal.

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/slits.html

## What is "Giancoli: Wave Nature of Light: Parallel Crests 2.5cm Apart" all about?

"Giancoli: Wave Nature of Light: Parallel Crests 2.5cm Apart" is a chapter in the textbook "Giancoli: Physics for Scientists and Engineers" that discusses the wave nature of light and specifically focuses on parallel crests that are 2.5cm apart.

## What is the wave nature of light?

The wave nature of light refers to the fact that light can behave like a wave, exhibiting properties such as interference, diffraction, and polarization. This is in contrast to the particle nature of light, which is described by the photon theory of light.

## How far apart are the parallel crests discussed in this chapter?

The parallel crests discussed in this chapter are 2.5cm apart. This distance is used as an example to demonstrate the properties of light waves, but the concepts discussed can be applied to any distance between parallel crests.

## How does the wave nature of light affect its behavior?

The wave nature of light affects its behavior in several ways. For example, light waves can interfere with each other, causing patterns of light and dark regions. Light waves can also be diffracted, or spread out, when they pass through a narrow opening or around an obstacle. Additionally, the polarization of light waves can be manipulated by passing them through certain materials.

## What real-life applications rely on the wave nature of light?

The wave nature of light has many real-life applications. For example, it is essential in technologies such as lasers, fiber optics, and holography. It is also important in understanding the behavior of light in everyday phenomena, such as the colors we see and the way light reflects off of surfaces.

• Introductory Physics Homework Help
Replies
3
Views
3K
• Introductory Physics Homework Help
Replies
2
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
3K
• Quantum Physics
Replies
12
Views
3K
• Introductory Physics Homework Help
Replies
2
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
3K
• Classical Physics
Replies
29
Views
2K
• Classical Physics
Replies
4
Views
2K
• Quantum Physics
Replies
46
Views
2K