A microscope has an objective of focal length 2 cm, eyepiece of focal length 4 cm and the tube length of 40 cm. If the distance of distinct vision of eye is 25 cm, the magnification in the microscope is

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Correct answer: B. 125 — # Microscope Magnification Solution The magnification of a microscope depends on the focal lengths of its lenses and the tube length, following the standard formula for compound microscopes. **Step 1: Identify the Magnification Formula** For a compound microscope, the total magnification is the product of objective magnification and eyepiece magnification. M = m_o 	imes m_e = \frac{v_o}{u_o} 	imes \frac{D}{f_e} where the tube length L = v_o + u_e (approximately), D = distance of distinct vision = 25 cm, and f_e = focal length of eyepiece. **Step 2: Use the Standard Microscope Formula** For a microscope with tube length L , objective focal length f_o , and eyepiece focal length f_e , the magnification is: M = \frac{L}{f_o} 	imes \frac{D}{f_e} Substituting the given values: L = 40 cm, f_o = 2 cm, f_e = 4 cm, D = 25 cm: M = \frac{40}{2} 	imes \frac{25}{4} = 20 	imes 6.25 = 125 **The magnification of the microscope is 125.** **Answer: (B) 125**

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A. 100

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C. 150

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D. 250

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