Assessment: Quantum and Atomic Physics

In a conducting vacuum diode (heated cathode, positive anode), electrons flow from the cathode to the anode. In which direction does CONVENTIONAL current flow through the tube?

An atom has 20 protons and 20 neutrons. Find its mass number A.

Find the energy of a photon of blue light with a frequency of 6.5 × 10¹⁴ Hz (h = 6.63 × 10⁻³⁴ J·s). (Enter the coefficient × 10⁻¹⁹, e.g. for 4.31×10⁻¹⁹, enter 4.31.)

As a blackbody's temperature increases, what happens to its total emitted radiation and peak wavelength?

If Thomson's 'plum pudding' model had been correct, what result would Rutherford's alpha-scattering experiment have shown?

An isotope of uranium has an atomic number of 92 and 143 neutrons. Find its mass number.

Why do astronomers consider the discovery of the cosmic microwave background strong evidence for the Big Bang?

X-rays can penetrate soft tissue for medical imaging, while visible light cannot. What property of X-ray photons explains this?

Bohr's model proposed that electrons can only orbit at specific, quantized energy levels. Which experimental observation does this idea help explain?

By Hubble's Law, a galaxy's recession speed is proportional to its distance. Galaxy A recedes at 15,000 km/s; galaxy B recedes at 45,000 km/s. How many times farther away is galaxy B compared to galaxy A?