Straight ripples reach a gap between two barriers in a ripple tank. What do the ripples do beyond the gap?
Jocasta aims a beam of electrons, not light, at a very thin crystal. Electrons are matter: each one has mass and charge. On the screen behind the crystal, a pattern of bright rings appears.
In the waves topic, you saw diffraction: a wave spreads out after passing through a gap or around an obstacle, and spreading waves can overlap into patterns. This lesson sends matter, not light, through that test.
A beam of electrons passes through a thin crystal. The crystal's regular rows of atoms act like a set of narrow gaps.
If electrons were only tiny balls, the screen would show a small bright patch in line with the beam.
The screen shows rings instead: bright rings around the beam's line, the kind of stable pattern that spreading, overlapping waves make.
That is a diffraction pattern, made by matter.
An electron does not stop being matter. It still has mass and charge. Wave-particle duality means the wave picture is needed to explain some of its behavior.
Light is not the odd one out. Light and matter both show wave-particle duality, and the next lessons build on that.
A beam of neutrons passes through a thin crystal, and the screen behind it shows a ring pattern. What does the result show about neutrons?
Rings around the beam's line are a diffraction pattern, the mark of spreading, overlapping waves.
Neutrons are matter particles: each one has mass.
A matter particle making a wave-only pattern is showing wave-particle duality.
Neutrons also show wave-particle duality: they behave like waves in some experiments.
Kenji expects the electron beam to leave one small bright patch behind the crystal. What does his expectation assume?
A small patch in line with the beam is what a stream of tiny balls would leave: each ball carries straight on through a gap.
The screen shows rings instead, the pattern of spreading, overlapping waves.
So the balls-only assumption fails for electrons.
Kenji's expectation assumes electrons only ever behave like tiny balls, and the ring pattern shows that assumption is wrong.
A beam of electrons passes through a thin crystal. What appears on the screen behind the crystal?
Which statement do electron-diffraction experiments support?
Kenji says: 'Wave-particle duality is not only for light. Matter particles such as electrons show it too.' Is Kenji correct?
An electron beam at a thin crystal produces a ring pattern on a screen. Which statement says what this shows?
If electrons only ever behaved like tiny balls, what would the screen behind the thin crystal show?
A beam of helium atoms passing a fine grid also builds a spread, patterned arrangement on a detector. What does this show?