Physics Dawn of Modern Physics DUHS 2023
PMDC Verified Question 22 of 52
If the wavelength of a light is \( 3 \times 10^{-7} \text{ m} \), then what is its frequency?
A
\( 1 \times 10^{15} \text{ Hz} \)
B
\( 1 \times 10^{13} \text{ Hz} \)
C
\( 1 \times 10^{14} \text{ Hz} \)
D
\( 1 \times 10^{16} \text{ Hz} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( 1 \times 10^{15} \text{ Hz} \)
Concept:

The wave speed equation relates the constant speed of light to its frequency and wavelength.

Formula:

$$ c = f\lambda \implies f = \frac{c}{\lambda} $$

Solution:

  • Using \( c = 3 \times 10^8 \text{ m/s} \) and \( \lambda = 3 \times 10^{-7} \text{ m} \).


  • \( f = \frac{3 \times 10^8}{3 \times 10^{-7}} \).


  • The coefficients cancel: \( 3/3 = 1 \).


  • Subtract the denominator exponent from the numerator: \( 8 - (-7) = 15 \).


  • The frequency is exactly \( 1 \times 10^{15} \text{ Hz} \).


Why other options are incorrect:

The alternative options reflect simple arithmetic errors in handling the subtraction of negative exponents.

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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