An electric field is an electric property associated with each point in space when charge is present in any form.
Physical changes are those change which just externally or physically change the state of the object . for example : water boils and evaporates... here the state is just changing from liquid to vapour while the composition is the same.
chemical changes are those which bring about a change in the composition of a substance. for example: burning of paper changes into ash .
Answer:
The wavelength of light is 
Explanation:
Given that,
Angle = 13.1°
Number of slits = 5000
We need to calculate the wavelength of light
Diffraction of first order is defined as,
.....(I)
The separation of the slits



Now put the value in equation (I)

Here, n = 1

Hence, The wavelength of light is 
B. it was necessary to see data from more plants before the conclusion could be accepted.
The granite would be older. As millions of years go by, rocks are affected by weathering and erosion. These processes break down rocks and scatter them. Rocks are broken down into sediments, which mix with other layers, which could have been the reason how the layer of sandstone contains the small fragments of granite.