Question

Error due to eye vision is termed as-
(A). Climax error
(B). Sight error
(C). Parallax error
(D). Visional error

Answer 1

Hint: Viewing from different lines of sight can give us an error in our readings. Parallax causes us to view a different reading than the original one because the apparent position changes along different lines of sight. It depends on the angle from which we are observing the object with respect to the scale.

Complete answer:
Many times when measuring the length of an object, we can make a mistake while reading the scale. This is because the scale needs to be in the direct line of sight of our eyes, otherwise, the readings we tend to see are more or less than the actual reading which gives us an error.
Parallax is the apparent change in the position of an object when we view it from different lines of sight. Parallax error occurs when we view an object at an oblique angle with respect to the scale; due to this the object appears to be on a different position on the scale.
To give you an example of parallax, when travelling in a car, the person on the driver seat will see the correct readings on a needle- style speedometer because it is directly in his line of sight but a person sitting on the passenger seat may read the readings incorrect due to the angle of viewing.
Parallax also affects optical instruments like telescopes, binoculars, microscopes, rifle scopes, twin-lens reflex cameras etc.
Viewing objects closer to you are likely to have a greater parallax error than viewing faraway objects.
Some ways to reduce parallax are-
Orient your eyes in such a way that your eyes, the object and the markings form a vertical line.
Always place the measuring device on it’s edge so that it is in level with the object.
While measuring the liquid, read the markings for lower meniscus.

Therefore, the correct option is C- parallax error.

Note:
There are other phenomena too which leads to error in vision; Myopia, also called near-sightedness, is a condition in which you can see near objects clearly but the farther objects appear to be blurry. Hypermetropia, also called far-sightedness, is a condition where you can see far away objects clearly but nearby objects are blurry. Astigmatism is a condition where the eye cannot focus light evenly on the retina which results in dispersed vision in any distance.