Benda setinggi 6 cm berada di depan cermin cekung yang berjari-jari 30 cm. Bila jarak benda ke...

Summary

This physics video explains the process of determining the image formation in a concave mirror. Given a 6 cm tall object placed 20 cm from a concave mirror with a focal length of 15 cm, the video guides the viewer through the mirror equation and magnification formula. It demonstrates how to calculate the image distance and magnification, with a final image height of 18 cm. The lesson emphasizes the relationship between object distance, image distance, and magnification, making it a valuable resource for understanding mirror optics.

Takeaways

• 😀 The object has a height of 6 cm, denoted as H.
• 😀 The object is placed 20 cm away from the concave mirror, denoted as S.
• 😀 The mirror has a radius of curvature of 30 cm, denoted as R.
• 😀 The focal length of the mirror is half the radius of curvature, so f = 15 cm.
• 😀 The focal length is positive since it's a concave mirror.
• 😀 To find the image distance (S'), the mirror equation is used: 1/f = 1/S + 1/S'.
• 😀 Substituting the known values into the mirror equation gives S' = 60 cm.
• 😀 The magnification (m) is calculated as the absolute value of S' divided by S, resulting in m = 3.
• 😀 Another formula for magnification is the ratio of the image height (h') to the object height (H).
• 😀 Using the magnification, the image height (h') is calculated to be 18 cm.
• 😀 The correct answer for the image height is 18 cm, matching option (d).

Q & A

What is the height of the object in the problem?

The height of the object is 6 cm, denoted as H in the script.

What is the distance of the object from the mirror?

The distance of the object from the mirror is 20 cm, denoted as S in the script.

What is the radius of curvature of the mirror?

The radius of curvature of the mirror is 30 cm, denoted as R in the script.

How is the focal length of the mirror related to its radius of curvature?

The focal length is half of the radius of curvature, so the focal length is 15 cm.

What is the equation used to find the image distance?

The equation used is the mirror equation: 1/f = 1/s + 1/s', where f is the focal length, s is the object distance, and s' is the image distance.

What is the image distance calculated in this case?

The image distance is calculated to be 60 cm (s' = 60 cm).

How is the magnification of the image determined?

The magnification is determined using the formula: m = |s'/S|, where s' is the image distance and S is the object distance. In this case, m = 60/20 = 3.

What is the magnification value in this problem?

The magnification value is 3 times, indicating the image is three times larger than the object.

What is another formula to calculate magnification?

Another formula for magnification is |h'/H|, where h' is the height of the image and H is the height of the object.

What is the height of the image calculated in this case?

The height of the image is 18 cm (h' = 18 cm), calculated by multiplying the magnification by the object's height.