Question

1. What is meant by the focal length of a lens or a mirror? What is the difference between a real image and a virtual image?

2. What are principal rays? Sketch them and explain each.

Answer #1

Focal Length -

The **focal length** of an optical system is a measure
of how strongly the system converges or diverges light. If the
Focal length is short ,then the rays are bended more sharply as
compared to Long Focal length.

Focal Length for a thin lens is given by -

1/f = 1/di + 1/do

f = Focal Length of Lens

do = Distance of Object from lens.

di = Distance of image from lens.

For a converging lens (for example a convex lens), the focal length
is positive.

For a diverging lens (for example a concave lens), the focal length
is negative.

For a spherically curved mirror in air, the magnitude of the focal
length is half the radius of curvature of the mirror.

f = R/2

The focal length is positive for a concave mirror, and negative for
a convex mirror.

**Difference between a real image and a virtual image
-**

- Real Image can be actually formed on Screen.
- Light Rays After Refraction meet .
- Real Image is Inverted.

- Virtual Image cannot be formed on Screen.
- Light Rays Do not meet after Refraction .
- Virtul Image is Erect.

*Please post seperate question in seperate post.*

1)
explain difference between a lens and a mirror; the difference
between converging lens and diverging lens; the difference between
virtual image and real image.
2) when standing in front of a flat mirror, how far away from
your eyes does your image appear to be? is this image virtual or
real? How can you tell?
Please answer every part of questions.

1. A converging lens has a focal length of 14 cm. An object is
18 cm to the left of the lens.
Find the image position
The magnification
Real or virtual?
Erect of inverted?
e. Draw the ray diagram using principal rays and a ruler.
f. If the object was located 7 cm to the left of the lens, draw
the ray diagram.

5. A biconvex lens with a focal length of 8cm has an object
which is 24 cm to the left of the lens.
(a) Sketch the lens and object – label the principal axis,
optical axis, optical center
(b) Using suitable rays presented in class, show on your sketch
in (a) where the image is expected to be
(c) Based on your sketch in (b) describe the characteristics of
the expected image
(d) Use the lens maker and magnification equation...

A convex mirror has a focal length of magnitude f. An object is
placed in front of this mirror at a point 2/3 f from the face of
the mirror. The image will appear:
upright and enlarged
upright and reduced
behind the mirror
A rocket is zooming by earth and there is pendulum in rocket.
observer a is on earth. observer b on rocket. observer a looks at
pendulum and sees period as TA. Observe B sees period as TB....

An object is 2 m to the left of a lens of focal
length 0.98 m. A second lens of focal length
-2.7 m is 0.36 m to the right of
the first lens. Find the distance between the object and the final
image formed by the second lens.
_____________
What is the overall magnification (with sign)?
Is the final image real or virtual?
Is the final image upright or inverted?

1. If an object is inside the focal point of a concave mirror,
the (answer choices: image will be inverted, image will be real,
image distance will be greater than the object distance, or
magnification will be less than 1)?
2. A diverging lens has a of focal length of -58.5 cm. A real
object is placed 25.3 cm in front of the lens.
a.) What is the image distance?
b.) Which side of the lens is the image located...

1. If an object is inside the focal point of a concave mirror,
the (answer choices: image will be inverted, image will be real,
image distance will be greater than the object distance, or
magnification will be less than 1)?
2. A diverging lens has a of focal length of -58.5 cm. A real
object is placed 25.3 cm in front of the lens.
a.) What is the image distance?
b.) Which side of the lens is the image located...

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The height of the object of is 3.6 cm.
What is the location of the final image with respect to the
second lens?
What is the height of the image?
Also determine is the image real or virtual and, with
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A diverging lens with a focal length of -19.7 cm and a
converging lens with a focal length of 11.0 cm have a
common central axis. Their separation is 39.5 cm. An
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the diverging lens, on the common central axis. Find the location
of the final image produced by the combination of the two
lenses.
Where is the image located as measured from the converging
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What is the...

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Find the distance between the object and final image formed by
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Is the final image real or virtual? Upright or inverted?

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