Register to reply

Question from simple lens diagram (camera)

by ZedCar
Tags: camera, diagram, lens, simple
Share this thread:
ZedCar
#1
May2-10, 01:21 PM
P: 342
1. The problem statement, all variables and given/known data
A simple camera has a converging lens of focal length 50.0 mm.

It is used to photograph a tree 3.00 m high.

The tree is 8.00 m away from the lens.

Calculate the distance v between the lens and the film, giving your answer in mm to three significant figures.


2. Relevant equations

1/f = 1/u + 1/v

3. The attempt at a solution

1/50 = 1/8000 + 1/(-v)
v = -50.3 mm

Is this correct? Thank you!
Phys.Org News Partner Science news on Phys.org
Wildfires and other burns play bigger role in climate change, professor finds
SR Labs research to expose BadUSB next week in Vegas
New study advances 'DNA revolution,' tells butterflies' evolutionary history
Squeezebox
#2
May2-10, 01:33 PM
P: 58
Why did you reason that the image distance was negative?
ZedCar
#3
May2-10, 01:57 PM
P: 342
Hmmm, not sure why I done that actually...

Have corrected to:

1/f = 1/u + 1/v

1/50 = 1/8000 + 1/v

v = 50.3 mm

Squeezebox
#4
May2-10, 01:58 PM
P: 58
Question from simple lens diagram (camera)

That looks right. The negative image distance you got before implies that the film needed to be outside the camera to capture the image.
ZedCar
#5
May2-10, 02:06 PM
P: 342
Thanks Squeezebox!

When I want to calculate the linear magnification of the image, the following equation is used:

m = v/u

Do I use the same v and u values from above? (both in metres)

i.e.

0.0503 / 8 = 0.0063
Squeezebox
#6
May2-10, 02:11 PM
P: 58
Quote Quote by ZedCar View Post
Thanks Squeezebox!

When I want to calculate the linear magnification of the image, the following equation is used:

m = v/u

Do I use the same v and u values from above? (both in metres)

i.e.

0.0503 / 8 = 0.0063
Now you have the opposite problem. There's a negative sign in this one.

m= -v/u

The image gets flipped upside down. This happens with your eyes too; your brain flips the image back right side up.
ZedCar
#7
May2-10, 02:28 PM
P: 342
Ah, so it'd be

-0.0503 / 8 = -0.0063

So is the height of the tree, stated in the question as being 3.00 m, not required to obtain the linear magnification?


Register to reply

Related Discussions
Camera zoom lens problem Introductory Physics Homework 6
Camera Lens Problem Introductory Physics Homework 1
Camera lens problem Advanced Physics Homework 3
Moving the Lens of a Camera Introductory Physics Homework 2
Optics: building a camera with quasi-hemispherical recording surface, what lens? General Physics 1