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== Chapters 34 (Young's Double Slit) and Section 35-11 (Polarization) == == Lecture 14: Chapters 34 (Young's Double Slit) and Section 35-11 (Polarization) ==


== Gone fishing, 1 ==

To shoot a fish with a gun, how should you aim?

<<c>>
<<lia(fishing_1.png, align = center)>>
<<c(1)>>

 A. aim directly at the image
 A. aim slightly above
 A. aim slightly below

Ans: C. Due to Snell's law, the fish looks higher than it really is.

== Gone fishing, 2 ==

To shoot a fish with a '''laser''' gun, how should you aim?

<<c>>
<<lia(fishing_2.png, align = center)>>
<<c(1)>>

 A. aim directly at the image
 A. aim slightly above
 A. aim slightly below

Ans: A.

== Superposition ==

<<c>>
<<lia(superposition.png, align = center, width = 50%)>>
<<c(1)>>

== Phase difference ==

The two waves shown are

<<c>>
<<lia(phasediff.png, align = center)>>
<<c(1)>>

  A. out of phase by $\pi$.
  A. out of phase by $\pi / 2$.
  A. out of phase by $\pi / 4$.
  A. in phase.

Ans: B. One wavelength corresponds to $2\pi$. Quarter wave length difference here.

== Young's double slit experiment ==

An interference pattern is seen from two slits. Now, cover one slit with glass, introducing a phase difference of $\pi$ (180$^\circ$; half wavelength) at the slits. How is the pattern altered?

<<c>>
<<lia(double_slit.png, align = center)>>
<<c(1)>>

  A. pattern vanishes.
  A. pattern expands.
  A. bright and dark spots are interchanged.
  A. no change at all.

Ans: C. Oveall phase difference is what matters.

== Young's double slit experiment ==

In a double slit experiment, if the wavelength of the light is increased, the interference pattern will

  A. spread out.
  A. shrinks together.
  A. stays the same.
  A. disappears.

Ans: A. $d\sin \theta = m \lambda$.

Lecture 14: Chapters 34 (Young’s Double Slit) and Section 35-11 (Polarization)

Gone fishing, 1

To shoot a fish with a gun, how should you aim?

Inlined image: fishing_1.png
  1. aim directly at the image
  2. aim slightly above
  3. aim slightly below

Ans: C. Due to Snell's law, the fish looks higher than it really is.

Gone fishing, 2

To shoot a fish with a laser gun, how should you aim?

Inlined image: fishing_2.png
  1. aim directly at the image
  2. aim slightly above
  3. aim slightly below

Ans: A.

Superposition

Inlined image: superposition.png

Phase difference

The two waves shown are

Inlined image: phasediff.png
  1. out of phase by $\pi$.

  2. out of phase by $\pi / 2$.

  3. out of phase by $\pi / 4$.

  4. in phase.

Ans: B. One wavelength corresponds to $2\pi$. Quarter wave length difference here.

Young’s double slit experiment

An interference pattern is seen from two slits. Now, cover one slit with glass, introducing a phase difference of $\pi$ (180$^\circ$; half wavelength) at the slits. How is the pattern altered?

Inlined image: double_slit.png
  1. pattern vanishes.
  2. pattern expands.
  3. bright and dark spots are interchanged.
  4. no change at all.

Ans: C. Oveall phase difference is what matters.

Young’s double slit experiment

In a double slit experiment, if the wavelength of the light is increased, the interference pattern will

  1. spread out.
  2. shrinks together.
  3. stays the same.
  4. disappears.

Ans: A. $d\sin \theta = m \lambda$.