4.3 Interference Patterns (7/9)

Question 1

Dutch scientist Christiaan Huygens (1629 - 1695) suggested that light was a)_____________.

However, Isaac Newton believed that light was b)____________. Owing to Newton’s stature, his views prevailed for a long time.

In 1801, English physicist Thomas Young (1773-1829) did what we now refer to as the c)____________________________, PROVING that light was d)_____________.

Answer 1

a) wave
b) made of particles
c) double slit experiment
d) a wave

Question 2

If light was only a particle, what pattern would shine on the screen during the double slit experiment? What pattern actually occurs?

Answer 2

a) Two bright stripes of light (one through each slit)
b) A wide band of dark and light stripes (with the brightest stripe in the middle)

Question 3

During the double slit experiment, what causes light waves to spread out into a WIDE band of light on the screen? (And not just shine straight through the slits forming two stripes of bright light)

Answer 3

DIFFRACTION

Because of diffraction, the light waves bend and radiate out in many directions.

Question 4

Draw the set-up of the double slit experiment. Include a) the light source, b) the metal with two slits, c) the screen, d) the light waves before the slit, and after.

Answer 4

Question 5

What is the experiment called that proved light acts like a wave?

Answer 5

The double slit experiment

Question 6

Draw a line through the light waves where maximum constructive interference occurs…

Answer 6

Question 7

What causes the dark bands in the double slit experiment?

Answer 7

destructive interference

Question 8

Write a test question using this equation. Include a “trick” of some kind to see if students are really paying attention.

Question 9

Why is this diagram not exactly accurate for the double slit experiment? Hint: what’s wrong with the light source waves?

Answer 9

This one is more accurate because the experiemnt uses one light source (to create the strongest constructive and destructive interference patterns). This means the light waves aren’t plane waves.

Question 10

Describe L in the diagram below

Answer 10

The length of the distance between the screen and the slits

Question 11

What is x in the diagram below?

Answer 11

The distance from the central line to the first fringe

Question 12

What is d in the diagram below?

Answer 12

The distance between the two slits

Question 13

Where is the central line?

Answer 13

The bright line in the middle

Question 14

What variable does this line represent in the equation for the double slit experiment?

Answer 14

X