Physics Light Part 17 (Question 2) Class 7 VII

TL;DR

This lesson explains the concept of virtual images, the differences between convex and concave lenses, and the uses of concave and convex mirrors.

Transcript

hello friends this video on light part 17 is brought to you by example.com no more fear from exam question number six what is a virtual image give one situation where a virtual image is formed so in case of a virtual image the reflected rays do not do not meet at the point but they appear to meet so these images cannot be obtained on the screen and... Read More

Key Insights

• 🙌 Virtual images are formed when reflected rays appear to meet but do not actually meet.
• 🙂 Convex lenses are thicker in the middle and converge light rays, while concave lenses are thicker at the edges and diverge light rays.
• 🪩 Convex mirrors produce diminished, erect images and are used in car rear-view mirrors, while concave mirrors produce enlarged, erect images and are used in dentistry.
• 💁 Only concave mirrors can form real images, while convex mirrors can only form virtual images.
• 💁 Concave lenses always form virtual, diminished, and erect images, while convex lenses can form real or virtual images.
• 🌥️ A concave mirror can produce a virtual image larger than the object.

Questions & Answers

Q: What is a virtual image and how is it formed?

A virtual image is formed when reflected rays do not meet but appear to meet. These images cannot be obtained on a screen and are always formed on the opposite side of the mirror.

Q: What are the differences between convex and concave lenses?

Convex lenses converge light rays, causing them to appear to meet at a point. They are thicker in the middle and thinner at the edges. Concave lenses, on the other hand, diverge light rays, spreading them away from each other. They are thicker at the edges and thinner in the middle.

Q: What are the uses of concave and convex mirrors?

Convex mirrors are used in car rear-view mirrors because they produce diminished, erect images. Concave mirrors are used in dentistry as they produce enlarged, erect images when kept close to the object.

Q: Which type of mirror can form a real image?

Only concave mirrors can form real images at certain locations. Convex mirrors always form virtual images.

Q: Which type of lens always forms a virtual image?

Concave lenses always form virtual, diminished, and erect images. Convex lenses can form real or virtual images depending on the object position.

Q: Which type of mirror can produce a virtual image larger than the object?

A concave mirror can produce a virtual image larger than the object.

Q: How does the distance between David and his image change when he moves towards a plane mirror?

When David moves one meter closer to the plane mirror, the distance between him and his image decreases by two meters. So if initially the distance was four meters, it would decrease to six meters.

Summary & Key Takeaways

• Virtual images are formed when reflected rays do not actually meet, but appear to meet. These images cannot be obtained on a screen and are always formed on the opposite side of the mirror.

• Convex lenses converge light rays, while concave lenses diverge them. Convex lenses are thicker in the middle, while concave lenses are thicker at the edges.

• Convex mirrors are used in car rear-view mirrors to produce diminished, erect images. Concave mirrors are used in dentistry to produce enlarged, erect images.