When an object is 10 cm in front of a lens, the image is located 45 cm in front

Question

When an object is 10 cm in front of a lens, the image is located 45 cm in front of the lens. Find the focal length of the lens. A. 22 cm B. 13 cm C. 8.0 cm D. 4.0 cm A diverging lens of focal length 85 cm produces an image from a real object. The image is 47 cm from the lens. Find the magnification of the image. A. -0.45 B. 0.45 C. 2.2 D. -2.2 A virtual object is located 50 cm from a diverging lens whose focal length has magnitude 40 cm. Find the image distance. A. 90 cm behind the lens B. 90 cm in front of the lens C. 200 cm behind the lens D. 200 cm in front of the lens

Explanation / Answer

24.

As per lens formula

1/f = 1/q - 1/p

And here p = -10 cm, q = -45 cm so

1/f = 1/(-45) - 1/(-10)

f = 12.85 = 13 cm, so correct option is B.

25.

As per lens formula

1/f = 1/q - 1/p

And here f = -85 cm, q = -47 cm so

1/p = 1/(-85) - 1/(-47)

p = -105.13 cm, and m = q/p = 0.447 so correct option is B.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.