Lenses: Measure f directly

f1 = 4.8 cm f2 = 12.7 cm f3= 25.2 cm

Lens f1 = 4.8cm
1/do + 1/di = 1/f = 1/8+1/11=19/88 hi / ho =2.7 cm/2.0 cm=1.35cm di / do = 11cm/8cm=1.35cm
% Error = [f - f calc/ f] x 100 = [4.8cm-4.6cm/4.8cm] x 100 =4%
% Error= [(hi / ho- di / do)/ (di / do)] x 100= [1.35-1.35/1.35] x 100= 0%
Lens f2 = 12.7cm
1/do + 1/di = 1/f = 1/22+1/29=51/638 hi / ho =2.5 cm/2.0 cm=1.3cm di / do = 29cm/22cm=1.3cm
% Error = [f - f calc/ f] x 100 = [12.7cm-12.5cm/12.7cm] x 100 =1.6%
% Error= [(hi / ho- di / do)/ (di / do)] x 100= [1.3-1.3/1.3] x 100= 0%
Lens f3 = 25.2cm
1/do + 1/di = 1/f = 1/42.1+/59.1= .041 hi / ho =2.5 cm/2.0 cm=1.3cm di / do = 59.1cm/42.1cm=1.4cm
% Error = [f - f calc/ f] x 100 = [25.2cm-25cm/25.2cm] x 100 =0.8%
% Error= [(hi / ho- di / do)/ (di / do)] x 100= [1.30-1.4/1.4] x 100=7.10%

Propose:
In this activity I will find focal lengths using the basic lens equation 1/do + 1/di = 1/f

Equipment:
Optics bench.
Light source.
Crossed arrow target.
Viewing Screen
3 Component Holders
3 lenses with focal length
-f1 = 4.8 cm
-f2 = 12.7 cm
-f3= 25.2 cm

Procedure

-Place the optics bench on the lab table.
- Turn on the light source.
- Move the 4.8 cm lens and its component holder back and forth on the bench until the Image is focused on the screen.
- Look for the best focus possible.
-Using a ruler, record the location of each of components on the bench.
-Use the ruler on the screen to measure the image for comparison
- Move the lens back and forth to find a good focus.
- Record the location of each of the components. Also note the size of the Image
-Before completing all the calculations, collect all the component locations for BOTH lenses and the mirror.
- For each trial