{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# PHY2 - Howard(clh2528 Homework#2 shubeita(57885 This...

This preview shows pages 1–3. Sign up to view the full content.

Howard (clh2528) – Homework #2 – shubeita – (57885) 1 This print-out should have 13 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001(part1of2)10.0points An object located 32 . 5 cm in front of a lens forms an image on a screen 10 . 5 cm behind the lens. Find the focal length of the lens. Correct answer: 7 . 93605 cm. Explanation: BasicConcepts: 1 p + 1 q = 1 f m = h h = - q p ConvergingLens f > 0 >p>f f <q< 0 >m> -∞ f >p> 0 -∞ <q< 0 >m> 1 DivergingLens f < 0 >p> 0 f <q< 0 0 <m< 1 Solution: The formula relating the focal length to the image distance s and the object distance s is 1 s + 1 s = 1 f so f = ss s + s = (32 . 5 cm) (10 . 5 cm) (32 . 5 cm) + (10 . 5 cm) = 7 . 93605 cm . 002(part2of2)10.0points What is the magnification of the object? Correct answer: - 0 . 323077. Explanation: Magnification is M = - s s = - (10 . 5 cm) (32 . 5 cm) = - 0 . 323077 . 003 10.0points S E F W P Q Which of the glass lenses above, when placed in air, will cause rays of light (par- allel to the central axis) to converge ? 1. F, S, and E 2. F, Q, and P 3. S and E 4. S and Q 5. F, W, and E 6. F, W, and Q correct 7. F, S, W, and P 8. F, E, and P 9. W and Q 10. F, S, Q, and P Explanation: convergent divergent Use the lensmakers’equation 1 f = ( n - 1) parenleftbigg 1 R 1 - 1 R 2 parenrightbigg , where R 1 and R 2 are + (or - ) if the center of curvature is behind (or in front of) the lens. To cause parallel rays of light to converge, f must be positive ( n> 1).

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Howard (clh2528) – Homework #2 – shubeita – (57885) 2 F: R 1 > 0 and R 2 = , = f > 0 , therefore convergent. S: R 1 = and R 2 > 0, = f < 0 , therefore divergent. W: R 1 > 0 and R 2 > 0, but | R 1 | > | R 2 | , = f > 0 , therefore convergent. E: R 1 < 0 and R 2 < 0, but | R 1 | < | R 2 | , = f < 0 , therefore divergent. Q: R 1 < 0 and R 2 < 0, but | R 1 | > | R 2 | , = f > 0 , therefore convergent. P: R 1 > 0 and R 2 > 0, but | R 1 | = | R 2 | , = f = , therefore neither convergent or divergent. Thus, lenses F, W, and Q are convergent lenses and Lenses S and E are divergent. Alternate(Elegant)Solution: ConvergingLens: The glass is thicker on the axis than at the edge. F, W, and Q satisfy these conditions for a converging lens ( f > 0). Diverging Lens: The glass is thinner on the axis than at the edge.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 6

PHY2 - Howard(clh2528 Homework#2 shubeita(57885 This...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online