Why the focal length of convex lens is always positive? The direction of the incident parallel rays and refracted rays in case of convex lens is the same. So, the distance of the point where the incident rays ,after passing through convex lens ,converge which is called focal length of the lens, is positive. This means convex lens does converge parallel incident rays.
Is the focal length positive or negative direction for a convex lens?
We can easily clarify that the focal length is positive direction for a Convex lens while negative with concave lens. Still have questions? cause of children to see the world only in terms of themselves and their own position A. ego centrism B. formal operations C .unconscious D. psychic …
Why is the power of convex lens positive?
Likewise, why the power of convex lens is positive? The power of a convex lens is positive as a convex lens has a positive focal length, while the power of a concave lens is negative as concave lens has a negative focal length. It is because focal length of convex lens is +ve and. Therefore power of convex lens is positive.
How do you find the focal length of a converging lens?
To measure the focal length of a converging (convex) lens. Using the formula: 1/u + 1/v = 1/f, the focal length f of the lens can be found.
What is the difference between a concave and convex lens?
When the image and object are at the two different sides of a lens the the focal length is positive. Example convex lens. When the object and images are at the same side (one side only) then the focal length is negative. Example concave lens. This is the general convention followed in lens optics.
Why the focal length of convex lens is positive and that of convex mirror is negative?
According to the Cartesian sign convention, the focal length should be positive since the convex mirror forms a virtual image to the right of mirror (positive direction) when light comes from left.
Why the focal length of convex lens is positive while concave lens has negative?
And for image distance, V in lens it is taken as positive in Convex lens since image is formed on +X side. It is taken as negative in Concave lens since image is formed in -X side of the Cartesian. In Concave mirror V is taken as positive and negative for convex mirror.
Why is the focal length of a convex lens negative?
For a convex lens, focal length (f) is positive and for a concave lens, the value of f is negative. So by assigning signs to focal length in the power formula (PL=1f) we get negative value for concave lens and positive value for convex lens.
Why is the focal length of a concave lens always negative?
Is concave lens positive or negative? The power of the lens is the reciprocal of the focal length. A concave lens is a diverging lens, so it will always have a negative focal length.
Why focal length of concave lens is positive?
For mirrors there is a slight difference in the formula of power but the meaning is the same. So the focal length of the concave mirror is negative. So, power for a concave mirror is positive. Also, the focal length of the convex mirror is positive.
Is the focal length of a convex lens positive or negative?
both convex mirror and convex lens have negative focal length.
Is focal length always positive?
The distance from the lens to the focal point is called the focal length. For converging lenses, the focal length is always positive, while diverging lenses always have negative focal lengths.
Why is focal length negative in diverging?
A converging lens causes exiting rays to be more convergent coming out than they were entering the lens. A diverging lens is said to have negative focal length. A diverging lens causes exiting rays to be more divergent coming out than thay were enetering the lens.
What makes focal length negative?
If an image appears on the opposite side of an object, the focal length is positive. Under this logic, concave mirrors and diverging lens have negative focal lengths.
Is convex positive or negative?
focal lengthobject distanceconcave mirrorpositivepositiveconvex mirrornegativepositiveconverging lenspositivepositivediverging lensnegativepositive
Is concave lens always negative?
Signs of u, v and f “f” is taken positive for convex lens and negative for concave lens. "u" is always taken negative. “v” is taken positive for real image and negative for virtual image.
Answer
I have a great deal of sympathy with your position. As taught in schools the sign convention is somewhat vague and that gets confusing with complicated setups.
Answer
Convex lens converges incident rays. Hence the rays to converge at a point in front of the lens. So image distance is positive here. We can easily clarify that the focal length is positive direction for a Convex lens while negative with concave lens.
