Practice question

Given: A compound microscope has an objective of focal length 2 cm and eyepiece of focal length 5 cm with a tube length of 18 cm . What is the magnification at infinity? These values define the system as per NCERT data. Formula: Objective magnification: m_o = L/f_o = 18/2 = 9. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Eyepiece magnification: m_e = D/f_e = 25/5 = 5 . Total magnification: m = m_o × m_e = 9 × 5 = 45 . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.