Questions – PASCO OS-8459 Beginning Optics System User Manual

Page 20

B e g i n n i n g O p t i c s S y s t e m

E x p e r i m e n t 7 : H o l l o w L e n s

Repeat this step with water in different section of the lens to complete the first
four rows of Table 7.1.

Dry the bottom of the hollow lens. Use double-sided adhesive tape to stick it to
the inside bottom of the transparent ray-optics box as shown in Figure 7.2. Cut a
strip of white paper about 5 cm × 15 cm; tape it to the inside bottom of the box as
shown. Position the light source outside of the box so that the rays enter the hol-
low lens through the flat side.

Figure 7.2: Hollow lens set up for testing surrounded by water

Fill the box with water to just below the top of the lens. Fill sections 2 and 3 of
the lens with water (leaving section 1 “filled” with air). Record your observation
in Table 7.1.

Repeat this step with air in different section of the lens to complete Table 7.1.

Questions

Under what conditions is a plano-convex lens converging? Under what condi-
tions is it diverging?

If a plano-concave lens of an unknown material is a diverging lens when sur-
rounded by air, is it possible to know whether the lens will be converging or
diverging when placed in water? Explain.

Table 7.1: Predictions and Observations

Lens

surrounded by:

Section 1

filled with:

Section 2

filled with:

Section 3

filled with:

Prediction

(converging or diverging)

Observation

(converging or diverging)

Air

Water

Air

Water

Air

Water

Air

Water

Air

Water

Air

Water

Air

Incident rays

Box

Hollow lens

Strip of paper

(5 cm x 15 cm)