Question

The parallax of a point ‘a’ on a pair of successive overlapping photographs is 73.22 mm and the micrometer reading of a parallax bar of point ‘a’ is 12.10 mm. Similarly, the micrometer reading of the parallax bar of point ‘b’ is 9.65 mm, then the parallax of the point ‘b’ is __________________ mm (round off to 2 decimal places).

Hint:

When dealing with parallax and micrometer readings, use the proportional relationship to find the parallax of other points.

Answer 1

Correct Answer: 70

The parallax of a point on overlapping photographs can be determined using the following relation: \[ \frac{P_a}{M_a} = \frac{P_b}{M_b} \] where: - \( P_a \) and \( P_b \) are the parallaxes of points ‘a’ and ‘b’, respectively. - \( M_a \) and \( M_b \) are the micrometer readings of points ‘a’ and ‘b’, respectively. Given that: \[ P_a = 73.22 \, \text{mm}, \quad M_a = 12.10 \, \text{mm}, \quad M_b = 9.65 \, \text{mm}, \] we can substitute these values into the equation to solve for \( P_b \): \[ P_b = \frac{P_a \times M_b}{M_a} = \frac{73.22 \times 9.65}{12.10} \approx 58.53 \, \text{mm}. \] Thus, the parallax of point ‘b’ is approximately 58.53 mm when rounded to 2 decimal places.