0
Focal length is related to the lens. It has nothing to do with how near or far the object is to the lens or objective.
Wiki User
∙ 12y ago
Add your answer:
Earn +20 pts
Why should the lens of a normal eye be fatter to look at near objects and thinner to look at distant objects?
The muscles around the lens of your eye push and pull it thicker and thinner to focus your eye on an object depending on the distance from your eye to the object. The focal length of a fat lens is shorter than the focal length of a thin lens (the light rays are bent more sharply) When you focus binoculars, you are adjusting their focal length
Are rays perpendicular to the principal axis of a concave mirror converge at or near the focal point?
It should be parallel. Rays "parallel to the principle axis of a concave mirror converage at or near the focal point.
Is a solar furnace dangerous?
Provided you are nowhere near the focal point of the furnace then they are perfectly safe.
Galileo determined that all objects in free fall near the surface of the earth?
Because up to that time, everybody knew that heavy objects obviously fall fasterthan light objects do, and obviously hit the ground sooner than light objects do,except that everybody was wrong.
Would a shadow be longer noon in winter or noon in summer?
the shadow would be longer in the winter i couldn't tell you why, though
Why should the lens of a normal eye be fatter to look at near objects and thinner to look at distant objects?
The muscles around the lens of your eye push and pull it thicker and thinner to focus your eye on an object depending on the distance from your eye to the object. The focal length of a fat lens is shorter than the focal length of a thin lens (the light rays are bent more sharply) When you focus binoculars, you are adjusting their focal length
How does the focal length of eye changes from a near object to far object?
When you're looking at a near object, the light rays converge at a point behind the retina so the focal length of your eye increases so that the parallel rays of light converge on the back of the retina. Therefore, if you're looking from a near object to a far object, the focal length of your eye should decrease back to its normal, relaxed size.
When the lens loses its elasticity and can no longer bring near objects in focus what is the condition?
Presbyopia
Define power of accomodation of the eye?
The difference of the near point and far point of vision of the eye. D= 1/Op - 1/Or The difference of the near point and far point of vision of the eye. D= 1/Op - 1/Or
How do bifocals help us today?
Bi means two, focal means to focus, so Bifocal glasses help you with both short sight and long sight.
What is the X in digital camera zooms?
The lens of a digital camera has a certain focal length, expressed in mm. For example, a 50mm lens has a field of view that approximates what we see with our eyes looking straight ahead. A 25mm wide-angle lens has a field of view that approximates what we see with our eyes when we turn our head from side to side. The shorter the focal length of a lens, the wider the field of view. The longer the focal length of a lens, e.g. 300mm, the narrower the field of view. Of course, a narrow field of view is equivalent to zooming in to a far object, like when we look into binoculars. A lens can either have a fixed focal length, e.g. 25mm, 50mm, 300mm, etc. or can have a range of focal lengths, e.g. 25mm - 100mm, 50mm - 300mm, etc. A lens that has a range of focal lengths is called a zoom lens. The zoom factor of the lens is calculated by dividing the maximum focal length by the minimum focal length. That zoom factor is the "X" you are referring to. For example: 1. A 25mm - 100mm lens is a 100/25 = 4x zoom lens. 2. A 50mm - 300mm lens is a 300/50 = 6x zoom lens. 3. A 50mm - 200mm lens is also a 200/50 = 4x zoom lens. 4. A 100mm - 400mm lens is also a 400/100 = 4x zoom lens. So knowing the zoom factor of a lens alone does not tell you what its minimum and maximum focal lengths are. Both examples 1, 3 and 4 above are 4x zoom lenses, but example 1 has a minimum focal length that is a wide-angle and allows us to take wide landscape shots or include all our classmates in one shot. Example 4 has a maximum focal length that is a long telephoto and allows us to bring far object near.
Are rays perpendicular to the principal axis of a concave mirror converge at or near the focal point?
It should be parallel. Rays "parallel to the principle axis of a concave mirror converage at or near the focal point.
What were bifocals made for?
Mostly for bank clerks .... Bifocals are glasses which have two focal points, one for near objects (reading) another for far away things. Older, "true" bifocals, have a separation line in the lens. New "varifocals" can habe more than 2 focal areas but need time to get used to ;-)
What is the orbit time around the earth?
Near the surface of the Earth, the time for an orbit is about one and a half hours. As objects (satellites) get farther, they would take longer for an orbit.Near the surface of the Earth, the time for an orbit is about one and a half hours. As objects (satellites) get farther, they would take longer for an orbit.Near the surface of the Earth, the time for an orbit is about one and a half hours. As objects (satellites) get farther, they would take longer for an orbit.Near the surface of the Earth, the time for an orbit is about one and a half hours. As objects (satellites) get farther, they would take longer for an orbit.
What is the similarities between the camera and the human eye in terms of the method of focusing near and far objects?
They're fundamentally different. -- The camera focuses for distance by changing the distance between the film and the rigid lens with fixed focal length. -- The eye focuses for distance by changing the shape, and thereby changing the focal length, of a soft lens, located a fixed distance from the retina. (Written by a contributor with two shiny new man-made intra-ocular lenses in place of his old cataracts. Seeing clearly is nice, but having no accomodation is weird. You other folks out there will never know it was there until it isn't there.)
Compare nearsightedness and farsightedness in terms of defects?
In nearsightedness, the eyeball is elongated and the focal point thus falls short of the retina. This results in good vision for objects very close to the face, but poor vision at any significant distance (even beyond a few feet, for any level of nearsightedness. Conversely, in farsightedness, the focal point is never reached, before the retina. Thus, objects which are near cannot be seen clearly. However, distance sight is preserved.
Is a solar furnace dangerous?
Provided you are nowhere near the focal point of the furnace then they are perfectly safe.
