Hello, readers welcome to new post. Here we will discuss Fsc 1st Year Physics Chapter 9 Solved Exercise.  In this post, we will discuss the chapter 9 exercise short question with details. That will help you to solve your papers. SO let get started

## Fsc 1st Year Physics Chapter 9 Solved Exercise

Q1: Solution

Two or more light sources work as coherent if there is no phase difference or have same phase difference between the waves released by them. A basic technique for making two coherent sources is to use of one source that illuminated the screen having two slits. Hence 2 or more sources produced by a single source are coherent since they have the same phase difference.

Q2: Solution

The fringe spacing or distance between two dark or bright fringes in young experiment given as

∆y=λL/d

λ is the wavelength of light L denotes distance between source and screen and d is the distance among slits. From equation, we can say that if the distance between slits large fringe spacing is less.

With the increment of d fringe spacing reduces and bright fringes come close such that light intensity is uniform and fringes diminish

Q3:Solution

Yes, it is possible white light can create fringes. As white light consists of seven colors and every color makes its fringes according to its wavelength.

The pattern of fringes will be colored but fringes will be such close that so it not possible to make difference between fringes of white light.

Q4:Solution

As red and blue light has different wavelengths also are not coherent so no dark and bright band will be created on the screen so interference of light can no be seen accurately. To get accurate interference use monochromatic light

Q5:Solution

A young double-slit experiment is used for discussion of bright light. Spreading of light about the corners of slit also creating the diffraction of light.  Interference on the screen occurs when light coming out from the narrow slits shows diffraction

Q6:Solution

The color is seen when oil spread on a wet path due to interference. When a light incident on oil some part of light is reflected from the upper part and some from the lower part of oil. These two reflected waves are coherent mean have the same phase difference.

When oil layer is thin reflected waves overlap so due to constructive and destructive interference colors produced.

Q7:Solution

Of course, newton rings can be generated through transmitted light. There is no phase changing that occurs in transmitted light. Hence bright fringes are replaced with dark fringes and so on.

For transmitted like light center point is bright.

Q8:Solution

In case of the diffraction grating, the equation will be

dsinθ=nλ

dsinθ is phase difference n is a number of order λ is the wavelength.

In case of 1st wavelength λ1 and 3rd order n value is 3

dsinθ=3λ1………1

for wavelength λ2 and 4th order n is four

dsinθ=4λ2…….2

Comparing equation 1 and 2 we have

3λ1=4λ2

λ1/λ2=4/3

λ1:λ2=4:3

Q9:Solution

In case of diffracting grating equation is

dsinθ=nλ

Here d is grating element and λ is wavelength

To get more order spactra from angle zero degrees to ninety degree d should be increased.

Q10:Solution

Light reflected from smooth surfaces such as water wet roads and lacks is horizontally polarized d and creates glare. Glare can be decreased by use of sunglasses. Since they decrease the light intensity passing through them.

So polarized glasses are better than ordinary glasses since reducing glare.

Q11:Solution

Unpolarized and polarized can be differentiated from one another through use of polarizers. If light views through the polarizer and can be viewed if the polarizer is rotated. Light viewed is not polarized. Thorugh on the rotation of the polarizer, light becomes dim and cut off through rotation of polarizer at 90 degrees. light seen is plane-polarized.