MDCAT Modern Physics MCQs 2026 | Photons, E = hf

What MDCAT 2026 asks in Unit 50 Dawn of Modern Physics

PMDC 14.1 is the photon. A photon is one quantum of EM radiation with energy $E=hf.$ Double the frequency, double the energy. Amplitude is not in the formula. Equivalently $E=hc/\lambda :$ violet packs more than red. A brighter red is more photons, not a more energetic photon.

Photoelectric effect is the experimental stick: below threshold frequency, no photoelectrons, however bright. KE of photoelectrons tracks frequency, not intensity. Intensity tracks the number of photoelectrons (once you are above threshold). Planck killed the ultraviolet catastrophe; classical 1/ $\lambda$ ⁴ blows up, a quantum of hf does not.

This quiz stays on that outcome — twenty labs about packets. Atomic spectra is Unit 15; nuclei are Unit 16.

• $E=hf$ = hc/ $\lambda$. $p=h/\lambda$ for a photon.
• Intensity ↔ number of photons. Frequency ↔ energy of each.
• Threshold frequency $f_0$: below it, no emission. $K_{\max }$ = hf − $\varphi$.
• Brighter light above threshold: more electrons, same $K_{\max }$.
• Photons have no charge and no rest mass in the MDCAT model.

Often-asked Dawn of Modern Physics MCQ patterns

These are the Dawn of Modern Physics ideas that keep coming every year with new numbers.

• Brighter light making each photon ‘heavier’.
• KE rising with intensity.
• Photons with charge or rest mass.
• Using $E=hf$ with f in the denominator.
• Red photons more energetic than violet because ‘red is hotter’.

Worked Dawn of Modern Physics numericals ($g=10)$

Work these on paper first. Then open the Unit 50 quiz — the same numbers are in the questions, with wrong options built from the usual mix-ups.

Dawn of Modern Physics traps that steal the mark

A good option is a true sentence about the wrong quantity. If you miss, the quiz names the mix-up on the option you actually picked.

• Brighter light making each photon heavier.
• KE rising with intensity.
• Photons with charge or rest mass in the MDCAT model.
• Using $E=hf$ with f in the denominator.
• Stopping potential depending on intensity instead of f.
• Sliding into spectra or nuclei inside a 14.1 stem.

Dawn of Modern Physics formula sheet for MDCAT 2026

Write these until they are cheaper than thinking. Then open the Dawn of Modern Physics quiz and make the picture agree.

• $E=hf$
• $E=hc/\lambda$
• $p=h/\lambda$
• $K_{\max }=hf-\varphi$

How to practise Unit 50 Dawn of Modern Physics MCQs

On every photon stem, write two columns: ‘how many’ (intensity) and ‘how energetic’ (f or $\lambda$). Put each fact in one column only.

For photoelectric, check threshold first. If hf < $\varphi$, the answer is zero electrons and you can stop.

Sit Dawn of Modern Physics after AC (spectrum) and before Atomic Spectra (what atoms do with those photons).

Choose topics and a test length up to 180 from the 715-question bank. Tutor Mode explains each selection; Timed Exam reveals explanations on submission. Use the complete review to revise mistakes and download your results.