The Young Double Slit Experiment and Superposition/Interference

Question 1

What is the principle of superposition

Answer 1

When two waves meet at a point the resultant displacement at that point is equal to the sum of the displacements of the individual waves

Question 2

Define coherence

Answer 2

Waves emitted from two sources having a CONSTANT PHASE DIFFERENCE

• same type
• same freq
• same wavelength

Question 3

Define interference

Answer 3

Superposition of waves from two coherent sources

Question 4

What is the equation for path difference

Answer 4

Extra distance travellled by one of the waves from the slits:
S1P - S2P

Where P is a commonnpoint both waves reach
S1 = slit 1

Question 5

What is the path and phase difference for constructive interference?

Answer 5

Path difference:
0, λ, 2λ
Integer multiple of λ

Phase difference:
0°/2π rad

Question 6

What is the path and phase difference for destructive interference?

Answer 6

Path difference:
λ/2, 3λ/2, (n + λ/2)λ

Phase difference:
180° or π rad

Question 7

How do u produce coherent, monochromatic light for young’s double slit experiment?

Answer 7

• use a candle, colour filter and a single slit then the double slit
• use a laser

Question 8

Define monochromatic light

Answer 8

Light of ONE wavelength

Question 9

Equation to find λ from Young’s double-slit experiment

Answer 9

λ = ax/D

a = seperation of slits
x = seperation of adjacent fringes
D = perpendicular distance from slits to screen

Question 10

How can you use the Young doible slit experiment to determine wavelength of sound?

Answer 10

Replace slits with loudspeakers

Question 11

How can you use youngs double slit experiment to determine λ of microwaves?

Answer 11

Place a trasmitter behind double slits (made of metal plates) and use a transmittor to detect