Although we have discussed single-slit diffraction only for a slit, a similar result holds when light bends around a straight, thin object, such as a strand of hair. In that case, a is the width of the strand. From actual laboratory measurements on a human hair, it was found that when a beam of light of wavelength 633.0nm was shone on a single strand of hair, and the diffracted light was viewed on a screen 1.40m away, the first dark fringes on either side of the central bright spot were 5.34cm apart. How thick was this strand of hair?

a = 16.5 x 10⁻⁶ m = 16.5 μm

Explanation:

Here we will use the diffraction equation:

y = mλL/a

where,

y = distance between two consecutive dark fringes = 5.34 cm = 0.0534 m

m = order of diffraction = 1

λ = wavelength of light = 633 nm = 6.33 x 10⁻⁷ m

L = Distance between hair and screen = 1.4 m

a = thickness of hair = ?

0.0534 m = (1)(6.33 x 10⁻⁷ m)(1.4 m)/(a)

a = (6.33 x 10⁻⁷ m)(1.4 m)/(0.0534 m)

a = 16.5 x 10⁻⁶ m = 16.5 μm

that would be because of both gravity and friction. so     c

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia