X-ray

Question 1

What is an X-ray?

Answer 1

X-rays are electromagnetic radiation with high energy and short wavelengths.

Question 2

How are X-rays produced?

Answer 2

X-rays are produced when thermally generated electrons from a heated filament are accelerated under a high potential difference towards an anode (tungsten) where they are abruptly stopped by collision with said anode.

Question 3

Describe the energy transformation in an X-ray tube.

Answer 3

Electrical energy –> thermal energy –> mechanical (kinetic) energy –> heat energy (99%) and electromagnetic wave (1%; x-rays)

Question 4

What is thermionic emission?

Answer 4

This is the emission of electrons from a heated metal surface.

Question 5

What are the agricultural uses of x-rays?

Answer 5

1. X-rays help determine the location and to what extent insect infestation is in seeds.
2. X-ray images can tell researchers the ability of a seed to germinate.

Question 6

Express Bragg’s law mathematically.

Answer 6

nλ = 2dsinθ

d = distance between atomic planes
λ = wavelength of scattered/diffracted X-ray
θ = glancing angle
n = number of order; 1, 2, 3,…, n

Question 7

What is the distance between atomic planes of FCCs (Face Centre Cubic)?

Answer 7

d = a ÷ (h² + k² + l²)^½

Where a = lattice constant
h, k, and l = given values of the atomic plane. That is, if it is said “The value of the X plane is 110”, then h, k, and l are 1,1, and 0 respectively.

Question 8

What are the characteristics of X-rays?

Answer 8

1. X-rays do not have charge, so they are not deflected in electric or magnetic fields.
2. X-rays have high frequencies and short wavelengths.
3. X-rays are electromagnetic waves; they can be refracted, deflected…
4. X-rays can go through/penetrate light materials.

Question 9

How can the total energy of an X-ray be calculated?

Answer 9

Energy = eV