Physics Nuclear Physics NUMS 2022
PMDC Verified Question 45 of 98
1 Gy is equal to:
A
\( 1 \text{ Jkg} \)
B
\( 1 \text{ Jkg}^{-1} \)
C
\( 1 \text{ J}^{-1}\text{kg} \)
D
\( \text{J}^{-1}\text{kg}^{-1} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( 1 \text{ Jkg}^{-1} \)


Concept:

The Gray (Gy) is the SI unit of absorbed radiation dose.

Formula:

$$ D = \frac{E}{m} $$

Solution:

  • Absorbed dose is defined as the amount of radiation energy absorbed per unit mass of tissue.


  • Energy (\(E\)) is measured in Joules (J). Mass (\(m\)) is measured in kilograms (kg).


  • Therefore, 1 Gray is exactly equivalent to absorbing 1 Joule of energy per kilogram of tissue.


  • This is written as \( 1 \text{ J/kg} \) or mathematically as \( 1 \text{ J kg}^{-1} \).


Why other options are incorrect:

Option A implies multiplication (Joule-kilograms). Option C inverts the relationship (kg/J). Option D inverts both.

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