Textbook References: Oxford Text pp 353-357; Hamper Text pp - ; Cutnell & Johnson Text pp 868-373. Syllabus Outcomes Covered in This Lesson:

Understandings SL Students: Double-slit interference

Path difference
HL Students: Young's double slit experiment

Modulation of two-slit interference pattern by one slit-diffraction effect

Multiple slit and diffraction grating interference problems Thin film interference
Applications & Skills SL Students: Quantitatively describing double-slit interference intensity patterns HL Students: Qualitatively describing two-slit interference patterns, including modulation by one-slit diffraction effect Investigating Young’s double-slit experimentally Sketching and interpreting intensity graphs of double-slit interference patterns Solving problems involving the diffraction grating equation Describing conditions necessary for constructive and destructive interference from thin films, including phase change at interface and effect of refractive index Solving problems involving interference from thin films

Task 1# (Both SL & HL) Watch/Read & Explore

(i) Watch this video on Young's Double Slit Experiment (1 min)
(ii) Go to the PhET Wave Interference Simulation Use this simulation to explore double-slit interference (10 mins) (iii) Read about Double Slit Interference at: a) The Physics Classroom, OR b) Study Physics (12 mins)

Task 2: (Both SL & HL) Analyse Data ; Looking at Relationships Quantitatively (i) Click on this link to download a Data Sheet for Double Slit Experiment you will fill-in for this task. YOU MUST KNOW THIS EXPERIMENT. IT IS A MANDATED ONE & YOU CAN EXPECT TO GET A QUESTION ON IT IN YOUR PAPER 3 EXAMINATION!
(ii) Click on the link below to watch a screen-recording of the use of a simulation to gather data about how changing the screen-to-slit distance (D) affects the distance between the central bright band and the adjacent secondary bright band (s):
Eduweblabs Youngs Double Slit Experiment (15-20 mins)

Task 3: (Both SL & HL) Assess Understanding and Skills (i) Try answering these Examination-style Questions on Young's Double Slit. (15 mins) (ii) Check your responses against this ANSWER KEY. (5 mins) ONLY HL STUDENTS PROCEED PAST THIS POINT.
Task 4: (HL students only) Diffraction Gratings (From sub-topic 9.3 Interference) (i) Watch this study.com Video on Multiple Slit Diffraction (3 mins) (ii) Step through this Flash Presentation on Interference and Diffraction Gratings (5 min) (iii) Attempt these Problems on Diffraction Gratings (15 min) (iii) Check your answers against this Answer Key (5 mins)
Task 5: (HL students only) Thin Film Interference (From sub-topic 9.3 Interference) (i) Watch this Introductory Video on Thin Film Interference (7 mins) (ii) Go through this Powerpoint on Thin film Interference carefully (10 mins)
(iii) (Optional) If you are still not sure if you have the ideas behind thin film interference sorted, look over this Study.com Video on Thin Film Interference (3 mins)

(iv) Attempt these Problems on Thin film Interference (15 mins)

(v) Check your responses against this Answer Key (5 mins)

	Created by Jeffrey Piggott about 9 years ago

Combined SL & HL lesson on Double Slit Interference with additional activities on Diffraction Gratings and Thin Film Interference for HL students only.