Surname 9 Essay Example

  • Category:
    Physics
  • Document type:
    Assignment
  • Level:
    High School
  • Page:
    1
  • Words:
    640

Q.1 (4.55 x Surname 9) x (4.23 x Surname 9 1) = 0.32 x Surname 9 2 s

Speed = 2.24 x Surname 9 3 s; hence depth of water = (0.32 x Surname 9 4) x (2.24 x Surname 9 5

Depth = 71.68 m

Surname 9 6

Parallel rays of a monochromatic light of wavelength λ as shown in the figure above are incident on a diffraction grating, which has a slit separation distance of d.  If the grating has m lines per metre, the grating spacing is given by: d = Surname 9 7

The rays are diffracted at an angle θ to the normal of the adjacent slits. Light from A must be in phase with light from B. Hence; 

                                                AC = mλ, where m = 0, 1, 2, 3…

                                            AC = d sin θ

                                                d sin θ = mλ

Simplifying the equation; sinθ = Surname 9 8

Q.3 (b) sin θ = Surname 9 9
where
θ = angle = 15o

slit distance =Surname 9 10 ; slit per mm= 400 ; hence slit per cm = 400000

taking order of magnitude = 1 ; slit distance = Surname 9 11 = 2.5 x Surname 9 12

wavelength (λ)=
Surname 9 13 = Surname 9 14
= 6.47 x Surname 9 15 m

(c) number of orders visible = Surname 9 16

= Surname 9 17 = 1 order

5. (iii) E = hf

Where E = energy of an electron, h= plancks constant = 6.62 x Surname 9 18 J/s

f= frequency = 8.80 x Surname 9 19 Hz

E = (6.63 x Surname 9 20) x (8.80 x Surname 9 21) = 5.834 x Surname 9 22 J

Work function of metal = 2.6eV = (1.6 x Surname 9 23 x (2.6) = 4.16 x Surname 9 24J

Since the energy of the light is more than the work function of the metal, electrons will be dislodged from the metal.

6. (b) (i). h = Surname 9 25

Where h = plank’s constant

Surname 9 26 = change in energy of electron = (3 – 1)eV= 2eV = (1.6 x Surname 9 27 x (2)

= 3.2 x Surname 9 28 J

Surname 9 29 = change in frequency = (12 – 7) X Surname 9 30 = 5 x Surname 9 31 Hz

h = Surname 9 32 = 6.4 x Surname 9 33 whereas the ideal plank’s constant is 6.63 x Surname 9 34

(ii) work function = hf = 6.4 x Surname 9 35 x 4.39 x Surname 9 36 = 2.81 x Surname 9 37 J

(iii) Energy of electron = work function + kinetic energy

hf = wf + ke ; 6.4 x Surname 9 38 x 5 x Surname 9 39 = 2.81 x Surname 9 40 + ke;

Ke = ; (3.2 x Surname 9 41 — (2.81 x Surname 9 42 = 0.39 x Surname 9 43

Ke= Surname 9 44mv2 where m= mass of electron= 9.1 x Surname 9 45and V = velocity of electron

V =Surname 9 46Surname 9 47= 2.93 x Surname 9 48m/s

Surname 9 49Surname 9 50

Surname 9 51

(ii)
since hSurname 9 52= eV, this shows that wavelength is inversely proportional to the accelerating potential. Thus shorther wavelength X-rays are produced by increasing the accelerating potential difference.

hf= hSurname 9 53= eV where h = plank’s constant = = 6.63 x Surname 9 54 c= velocity of x-ray = 3 x Surname 9 55 m/s

eV= 50 x Surname 9 56 x 1.6 x Surname 9 57 = 8 x Surname 9 58

λ = Surname 9 59 = = 2.49 x Surname 9 60m

(iii) increase in acceleration potential in the x-ray would lead to an increase in the x ray intensity, increase in value of characteristic radiation and also a lower short wavelength limit

8. (a) kinetic energy = potential energy = q* v = ; (1.6 x Surname 9 61) x (6 x Surname 9 62 )= 9.6 x Surname 9 63

K.e = Surname 9 64mv2 = 9.6 x Surname 9 65

where m= mass of electron= 9.1 x Surname 9 66and V = velocity of electron

V =Surname 9 67Surname 9 68= 1.45 x Surname 9 69m/s

(b) De Broglie wavelength (λ) = = Surname 9 70 where h = plank’s constant = 6.63 x Surname 9 71

m= mass of electron = 9.1 x Surname 9 72and V = velocity of electron = 1.45 x Surname 9 73m/s

λ =
Surname 9 74 = 5.025 x Surname 9 75

Works cited

Born, Max, and Emil Wolf. “Principles of optics: electromagnetic theory of propagation,

interference and diffraction of light.” 7th expanded edition. Cambridge: Cambridge

University Press, 1999. 28-40

Bragg, William Henry, and William Lawrence Bragg. “X rays and crystal structure”. 4th ed.

London: G. Bell and Sons, ltd., 1924. 12-23

Compton, Arthur Holly, and Samuel King Allison.” X-rays in theory and experiment,” New

York: D. Van Nostrand company inc., 1935. 48-51

Cowley, J. M. “Diffraction physics” 2nd, rev. ed. Amsterdam: North-Holland Pub. Co. 1981.

Hammond, C. “The basics of crystallography and diffraction.” 2nd ed. Oxford: Oxford

University Press, 2001. 50-62