4. The type of lens used as a magnifying glass(a)Concave lens(b) Convex lens(c)Concavo-convex lens(d) Convexo-concave lens

Identifying the Correct Lens

To identify the type of lens used as a magnifying glass, let’s analyze the characteristics of each option provided:

1. Concave Lens: This type of lens diverges light rays and cannot form a magnified image. It is typically used for correcting vision, not magnifying objects.

2. Convex Lens: A convex lens converges light rays and is capable of forming a real and virtual image. When used as a magnifying glass, it creates a virtual image larger than the object, making it an effective choice for magnification.

3. Concavo-convex Lens: This is a combination of a concave and convex lens. It is often used in specific optical applications but not commonly for magnification purposes.

4. Convexo-concave Lens: Similar to the concavo-convex lens, this design features one convex and one concave surface and is typically not used for standard magnification.

Conclusion

Based on the above analysis, the correct answer is:

Final Answer: (b) Convex lens, as it is the type of lens used in a magnifying glass.