# A 5.00 cm high object is located 39 cm in front of a convex lens of focal length 20.0 cm.?

Can someone please help!

a) A 5.00 cm high object is located 39 cm in front of a convex lens of focal length 20.0 cm.

Image distance_______cm

Magnification

Image size__________cm

Image type

Image orientation

b) A 5.00 cm high object is located 39 cm in front of a convex lens of focal length 60.0 cm. Image distance_______cm

Magnification

Image size__________cm

Image type

Image orientation

c) A 10.0 cm high object is located 39 cm in front of a concave lens of focal length -20.0 cm.

Image distance_______cm

Magnification

Image size__________cm

Image type

Image orientation

d) A 10.0 cm high object is located 39 cm in front of a concave lens of focal length -60.0 cm.

Image distance______cm

Magnification

Image size__________cm

Image type

Image orientation

Thanks!

### 2 Answers

- FootmanLv 67 years agoFavorite Answer
A 5.00 cm high object is located 39 cm in front of a convex lens of focal length 20.0 cm.?

I will do the first one and you get the idea and attempt the rest yourself.

However I give you my EXCEL file with the answers see first LINK.

If you get stuck EMAIL me, though the last time I said that I got 10 points deducted, never found out why but I still say it anyway.

Basic Lens equation (All things MUST be in the same units eq cm)

1/f = 1u + 1/v

f is the focal length of the lens put NEGATIVE for a CONCAVE (diverging) lens

u is distance from lens to the object on the left hand side of the lens (put negeative if on the right).

v is distance from lens to the image on the right hand side of the lens. (will be negative if image on the left of the lens)

Mag = -v/u (negative because image is upside down)

So in our case we have

1/20 = 1/39 + 1/v

1/v 1/20 – 1/39

v = 41.052 cm to 2 dp to RIGHT of lens using calculator. keep number for mag calculation

As V is positive this means the image is REAL

Mag = -41.052 / 39 = -1.053x to 2 dp keep number for image size calculation

Image Size = 5*Mag = -5*1.053 = -5.263 cm

As this is negative this means the image is upside down (INVERTED)

Source(s): https://dl.dropbox.com/u/94150610/Lens.xls http://www.physicsclassroom.com/class/refrn/u14l5f... (Wikipedia is too complicated for this) - ghadimiLv 43 years ago
No image will be formed because it truly is going to seem blurry. he focal length of a lens is the point at which parallel gentle rays (infinity gentle) will converge after passing by potential of the lens. Like protecting a well-known magnafying glass to concentration the daylight beam. if the lens is too faraway from the floor, the picture voltaic is only a scattered brightness that really purely delivers illumination. once that magnifying glass is wanting to the right focal length of that convex lens, then the picture voltaic is able to burning leaves. it truly is because the parallel lightrays of the suns gentle is further to a sharp concentration. The lens does this to gentle =()> or <()=