The focal length of a convex lens is f. An ob | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(C) The focal length of the convex lens is given as $f$. The object is placed at a distance $x$ from the first focal point. Since the first focal poin

Vedclass · Accepted Answer

$\frac{f}{x}$

Vedclass · Answer

(C) The focal length of the convex lens is given as $f$. The object is placed at a distance $x$ from the first focal point. Since the first focal point is at a distance $f$ from the optical center,the total object distance $u$ from the optical center is $u = -(f + x)$. Using the lens formula,$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$. Substituting $u = -(f + x)$,we get $\frac{1}{v} - \frac{1}{-(f + x)} = \frac{1}{f}$. $\frac{1}{v} = \frac{1}{f} - \frac{1}{f + x} = \frac{f + x - f}{f(f + x)} = \frac{x}{f(f + x)}$. Thus,$v = \frac{f(f + x)}{x}$. The magnification $m$ is given by $m = \frac{v}{u}$. $m = \frac{\frac{f(f + x)}{x}}{-(f + x)} = -\frac{f}{x}$. The ratio of the size of the real image to the object is the magnitude of magnification,which is $|m| = \frac{f}{x}$.

The focal length of a convex lens is $f$. An object is placed at a distance $x$ from its first focal point. The ratio of the size of the real image to that of the object is

Similar Questions

If the central portion of a convex lens is wrapped in black paper as shown in the figure,

The focal length of a lens is greatest for which colour?

$A$ convex lens forming a real image of magnification $m_1$ on a screen is moved through a distance $x$. $A$ new image of magnification $m_2$ is again formed on the screen. The focal length of the lens is:

$A$ convex lens $T$ is used to form an image whose size is one-fourth that of the size of the object. Then the object distance is (in $f$)

$A$ diminished image of an object is to be obtained on a screen $1.0 \ m$ from it. This can be achieved by appropriately placing

Vedclass Test Series

Exam Paper Generator

Online Exam Module