Turning Points - deBroglie

Question 1

What are features of light that indicate it behaves both as a wave and a particle?

Answer 1

Wave - Inteference, diffraction, polarisation

Particle - Photoelectric effect, electron diffraction

Question 2

What was deBroglie’s hypothesis?

Answer 2

That if “wave-like” light had particle properties, then it is expected that particles should have wave-like properties

Question 3

what does deBroglie’s equation relate?

Answer 3

it relates wavelength (a wave property) to momentum (a particle property)

lamda = h / mv

Question 4

Describe the process of electron diffraction

Answer 4

Diffraction patterns are observed when accelerated electrons in a vacuum tube interact with the spaces in a graphite crystal.

As they pass through the spaces, they diffract (just like waves passing through a narrow slit) and form a pattern of rings

This provides evidence of particles having wave properties

Question 5

How does the ring spacing change?

Answer 5

By changing the wavelength of the wave. The greater the wavelength the greater the ring spacing

Question 6

How is wavelength changed?

Answer 6

By changing the accelerating voltage of the electron beam (therefore changing the speed of the electrons)

Question 7

What is the diameter of an atom?

Answer 7

1x10^-10 m

Question 8

In Hertz’s experiment how was it shown that EM waves have magnetic property?

Answer 8

induced emf in the loop must be caused by changing magnetic
flux through the loop.

Magnetic flux change must be caused by the wave passing through the loop so the wave has a magnetic nature

Question 9

In Hertz’s experiment how was it shown that EM waves have electric property?

Answer 9

Another dipole aligned with the transmitter detects an
electric field which changes