Now use a parallel ray corring from the zight side of the lens to locate the focal point of the lens on the left side. Also rark this point with an $"$R$."$ is the focal length the same as you found in Question $2?$

Send a ray from the left side of the lens through the left side focal point and into the lens as shown below. Trace the ray onto the paper before and aiter it is refracted by the lens and label it on your paper as Ray $2.$

Huncer goug through the lens, is the refracted Ray $2$ parallell to the optical axis?

Send a ray directly through the center of the lens and trace the ray, luabel it as Ray $3$ on your paper.

Suncmaxite the behavion of each of these three rays $($called pxincipal rays$)$ after they pass through the converging lens.

Ray $1.$ a ray parallel to the optical axis $q,$

$q,$

Ray $2-$ a xay passing through the fromt$-$side focal point $q,$

$q,$

Ray $3.$ a ray passing throughth the center of the lems $q,$

$q,$

$2$ of $6$

Now we will use these three rays to construct a ray diagrame in order to locate an image. On a separate sheet of paper draw the optical axis and the lens plane. Use your measured value of the focal length to mark the left and right side focal points and label therr each $"3."$ Now draw an arnow with its base at the optical axis which has a height, h$,$ of $1\mathrm{.}0$ cm and is located $1\mathrm{.}5\mathrm{.}0$ cm from the center of the leas $(15\mathrm{.}0$ cmr will be the object distance, s$).$ This artow represents the object

We will use the ray tracing noethod to find the image. We do this by locating the inmage point for the tip of the object. This tells us where the tip of the image must be$.$ Use the ray box to create Ray $11$ which passes through the tip of the arrow and continues parallel to the optical axis unitil strilking the lens. Trace Ray $1$ onto your palper both before and after passing through the lems.

Use the same. techanique to find Rayy $2($passing through the tip of the arrow and through the lefit side focall point before striking the lens$)$ and Ray $3($passing through the tip of the arxow and then throught the center of the lens$).$ Trace Ray $2$ and Ray $3$ onto your: paper both before and after passing through the lens.

Do the three refracted rays cross at a single point? Yes or No$.$

If not, do they cross nearly at the sam.e point? Yes or No$.$

$12.$ This crossing point is the location of the tip of the im age. We lknow that the base of the object m$.$ usit lie on the optical axis. Draw an anrow with its tip at the crossing point and its tail at the opticall axis to represent the imnage.

$3$ of $6$