Which statement describes a convex lens?

Which statement describes a convex lens?

• A. Has a focal point on both sides of the lens
• B. Is thinner in the middle than at the edges
• C. Causes light to always diverge
• D. Bends light away from the normal in all cases

Answer: (A)

A convex lens is a converging lens: its shape is thicker in the middle than at the edges, so light rays entering it are bent toward the axis and come together at a focal point on the opposite side. Because there are focal points on both sides of the lens, parallel light from either side will eventually meet at a point on the other side. That means the statement describing a convex lens is that it has a focal point on both sides of the lens. The other ideas don’t fit because a convex lens is not thinner in the middle (that describes a concave lens), it does not always cause light to diverge (it actually converges parallel rays), and bending away from the normal in all cases isn’t correct since refraction depends on whether light is entering or leaving the lens and on the surfaces involved.

A convex lens is a converging lens: its shape is thicker in the middle than at the edges, so light rays entering it are bent toward the axis and come together at a focal point on the opposite side. Because there are focal points on both sides of the lens, parallel light from either side will eventually meet at a point on the other side. That means the statement describing a convex lens is that it has a focal point on both sides of the lens.

The other ideas don’t fit because a convex lens is not thinner in the middle (that describes a concave lens), it does not always cause light to diverge (it actually converges parallel rays), and bending away from the normal in all cases isn’t correct since refraction depends on whether light is entering or leaving the lens and on the surfaces involved.