Question

In the parallax method for measuring focal length, what action does the observer perform to locate the position of the image?

विकल्प

• Moves the optical device up and down

• Moves their head horizontally while observing the image through the optical device

• Rotates the optical device around its axis

• Adjusts the distance between the object and the light source

Answer 1

Moves their head horizontally while observing the image through the optical device

Explanation:

In the parallax method, the observer moves their head horizontally while observing the image through the optical device. When there is no relative shift between the image and the reference pin (no parallax), the image is located at the exact position of the pin, allowing accurate focal length measurement.