Q166 / 180 · COMEDK 2012 · Physics

A star A is 100 times brighter than star $B$. Then, $m_{B}-m_{A}$ the difference in their apparent magnitudes is

  • A
    100
  • B
    $0.01$
  • Correct answer
    C
    5
  • D
    $0.2$

Solution

Given, $\frac{I_{A}}{I_{B}}=100$ Using magnitude equation, $$ \begin{aligned} m_{B}-m_{A} &=-2.5 \log \left(\frac{I_{B}}{I_{A}}\right) \\ &=-2.5 \log \left(\frac{1}{100}\right)=-2.5 \times-2=5 \end{aligned} $$

Hence, the correct answer is option: 'C'.

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