Question

Focal length of objective lens and eyepiece lens are 1.25 cm and 5 cm and tube length is 26 cm. Find magnification of compound microscope in normal adjustment.

Hint:

For a compound microscope, the total magnification is the product of the magnifications due to the objective lens and the eyepiece. Use the tube length and focal lengths to calculate it.

Answer 1

Correct Answer: 104

The magnification of a compound microscope in normal adjustment can be calculated using the formula:

M = m_objective × m_eyepiece,

where:

• m_objective = L/f_objective
• m_eyepiece = 1 + (D/f_eyepiece)

Given:

• Focal length of the objective lens, f_objective = 1.25 cm
• Focal length of the eyepiece lens, f_eyepiece = 5 cm
• Tube length, L = 26 cm
• Distance of distinct vision, D (typically 25 cm for a relaxed eye)

First, calculate magnification due to the objective lens:

m_objective = L/f_objective = 26 cm / 1.25 cm = 20.8

Next, calculate magnification due to the eyepiece lens:

m_eyepiece = 1 + (D/f_eyepiece) = 1 + (25 cm / 5 cm) = 6

Now, calculate the total magnification:

M = 20.8 × 6 = 124.8

Upon review, the computed value of magnification, 124.8, does not fall within the expected range of 104,104 as mentioned. There may be a reconsideration of parameters or assumptions involved in defining the range.