Converging Lens Lab
Objective
The objective of this experiment was to find the focal length of two converging lenses separately and also to find the focal length of combination of two converging lenses. Another objective was to study the image formed by a converging lens plus diverging lens.
Background
This experiment focused on a simple lens system. A simple lens is a piece of glassware that is spherical on one side and flat on another side, or spherical on both sides. There are two different types of lenses. A converging lens, also called a positive lens, and a diverging lens, also known as a negative lens. A converging lens thicker middle area than top and bottom, and the diverging lens has a skinnier mid-section.
When a parallel ray passes through …show more content…
The focal length was calculated using equation 2. Below is a sample calculation for the focal length of Part I, trial 1. f = d¬ido¬ / (di + do) = (30.0cm * 19.0cm)/(30.0cm + 19.0cm) = 11.6cm
The magnification is given by the equation M = -hi / ho
Part I
Table 6 Focal length of converging lens A using the window as the object do(cm) 1/do(cm-1) di(cm) 1/di(cm-1) f1 (cm)
∞ 0 11 0.091 11
Table 7 Focal length of converging lens A
Trial do (cm) di cm) f1 (cm) ho hi -hi/ho -di/do
1 19.0 30.0 11.6 1.0 2.0 -2.0 -1.6
2 17.0 36.0 11.5 1.0 2.3 -2.3 …show more content…
Deviation={(|µ1- µavg|)+(|µ 2- µavg|)+(|µ 3- µavg|)}/3
= {(|6.83cm-6.88cm|)+(|6.84cm-6.88cm|) +(|6.97cm-6.88cm|)}/3
= ±0.06cm
Focal length = 6.88cm =6.88±0.06cm
The focal length of the experimental focal length of compound lens A and B was 6.88±0.06cm.
Calculation of compound lenses of A and B
The relationship of the focal length is given by equation 5 and using the focal length found in Part I
Rearranging the formula and isolating for fc: fc = (f1f2)/(f1 + f2) (equation 7) fc = (11.1cm*11.6cm)/(11.1cm + 11.6cm) fc = 5.67cm
The theoretical focal length for the converging lens A and B was 5.67cm.
%difference between the theoretical value and experiment value %difference = |(f.theory – f.exp)| / f.theory x 100% = |(5.67cm-6.88cm)| / 6.88 x 100% = 17.6%
The percentage difference between the theoretical compound focal length and experiment focal length was 17.6%.
Part
The objective of this experiment was to find the focal length of two converging lenses separately and also to find the focal length of combination of two converging lenses. Another objective was to study the image formed by a converging lens plus diverging lens.
Background
This experiment focused on a simple lens system. A simple lens is a piece of glassware that is spherical on one side and flat on another side, or spherical on both sides. There are two different types of lenses. A converging lens, also called a positive lens, and a diverging lens, also known as a negative lens. A converging lens thicker middle area than top and bottom, and the diverging lens has a skinnier mid-section.
When a parallel ray passes through …show more content…
The focal length was calculated using equation 2. Below is a sample calculation for the focal length of Part I, trial 1. f = d¬ido¬ / (di + do) = (30.0cm * 19.0cm)/(30.0cm + 19.0cm) = 11.6cm
The magnification is given by the equation M = -hi / ho
Part I
Table 6 Focal length of converging lens A using the window as the object do(cm) 1/do(cm-1) di(cm) 1/di(cm-1) f1 (cm)
∞ 0 11 0.091 11
Table 7 Focal length of converging lens A
Trial do (cm) di cm) f1 (cm) ho hi -hi/ho -di/do
1 19.0 30.0 11.6 1.0 2.0 -2.0 -1.6
2 17.0 36.0 11.5 1.0 2.3 -2.3 …show more content…
Deviation={(|µ1- µavg|)+(|µ 2- µavg|)+(|µ 3- µavg|)}/3
= {(|6.83cm-6.88cm|)+(|6.84cm-6.88cm|) +(|6.97cm-6.88cm|)}/3
= ±0.06cm
Focal length = 6.88cm =6.88±0.06cm
The focal length of the experimental focal length of compound lens A and B was 6.88±0.06cm.
Calculation of compound lenses of A and B
The relationship of the focal length is given by equation 5 and using the focal length found in Part I
Rearranging the formula and isolating for fc: fc = (f1f2)/(f1 + f2) (equation 7) fc = (11.1cm*11.6cm)/(11.1cm + 11.6cm) fc = 5.67cm
The theoretical focal length for the converging lens A and B was 5.67cm.
%difference between the theoretical value and experiment value %difference = |(f.theory – f.exp)| / f.theory x 100% = |(5.67cm-6.88cm)| / 6.88 x 100% = 17.6%
The percentage difference between the theoretical compound focal length and experiment focal length was 17.6%.
Part