Physics Dawn of Modern Physics MDCAT 2019
PMDC Verified Question 44 of 52
Calculate the energy of a photon of frequency \( 3.0 \times 10^{18} \text{ Hz} \). (\( h = 6.63 \times 10^{-34} \text{ Js} \))
A
\( 19.89 \times 10^{-18} \text{ J} \)
B
\( 11.89 \times 10^{-16} \text{ J} \)
C
\( 1.89 \times 10^{-16} \text{ J} \)
D
\( 19.89 \times 10^{-16} \text{ J} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( 19.89 \times 10^{-16} \text{ J} \)
Concept:

The fundamental relationship in quantum mechanics states that a photon's energy is its frequency scaled by Planck's constant.

Formula:

$$ E = hf $$

Solution:

  • Substitute the given values: \( E = (6.63 \times 10^{-34} \text{ Js}) \times (3.0 \times 10^{18} \text{ Hz}) \).


  • Multiply the coefficients: \( 6.63 \times 3 = 19.89 \).


  • Add the exponents: \( -34 + 18 = -16 \).


  • Result: \( E = 19.89 \times 10^{-16} \text{ J} \).


Why other options are incorrect:

Other options represent basic arithmetic errors in multiplication (yielding 11.89) or exponent addition (yielding \( 10^{-18} \)).

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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