Afree electron with initial energy of 9 ev encounters a rectangular potential step of energy 12 ev and width of 0.4 nm. what is the probability that the electron will tunnel the barrier ?

The  probability that the electron will tunnel the barrier is 0.25%.

Explanation:

Given that,

Initial energy = 9 eV

Potential energy = 12 eV

Width = 0.4 nm

Using formula of transmission coefficient

.....(I)

We need to calculate the value of k

Where, m = mass of electron

E = initial energy

v=potential energy

Put the value into the formula

We need to calculate the probability that the electron will tunnel the barrier

Using the formula of tunnel barrier

Where,

Put the value into the formula

Hence, The  probability that the electron will tunnel the barrier is 0.25%.

the answer is kevlar

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