2018 - WAEC Physics Past Questions and Answers - page 3

Rainbows are formed by the dispersion of light and reflection from drops of water in the atmosphere

The question asks to identify the type of lens illustrated. Without an image, it's impossible to identify the exact lens. However, based on the options, let's consider the possibilities: * **Converging meniscus:** A lens that is thicker at the center than at the edges and converges light rays. * **Plano-convex:** A lens with one flat surface and one convex (outwardly curved) surface. * **Diverging meniscus:** A lens that is thinner at the center than at the edges and diverges light rays. * **Bi-convex:** A lens with both surfaces convex (curved outwards). Without the image, the best logical deduction is to consider the common lens shapes. If the lens appears to curve inwards, it is a diverging meniscus. If it curves outwards, it can be converging or bi-convex, depending on the other surface. If one side is flat and the other curved outwards it is plano-convex. Therefore, a definitive answer is not possible without an image. However, given the options, the response that describes the lens shape correctly would be one of the converging or diverging meniscus or bi-convex or plano-convex depending on the shape.

Number of images = \(\frac{360}{n} - 1\)

where n is the angle of inclination.

Given the number of images = 11, we have

\(\frac{360}{n} - 1 = 11\)

\(\frac{360}{n} = 12\)

\(n = \frac{360}{12} =30°\)

Most capacitors contain at least two electrical conductors often in the form of metallic plates or surfaces separated by a dielectric medium.

Let \(h_{Q}\) and \(\rho_{Q}\) be the least length and the density of \(Q_{1}\) 

while \(h\) and \(\rho\) are the length and density of mercury respectively.

\(h\times \rho \times g = h_{Q} \times \rho_{Q} \times g\)

\(76cm \times 13.6 \times 10 = h_{Q} \times 16.2 \times 10\)

\(h_{Q} = \frac{76\times13.6\times10}{16.2\times10}\)

\(h_{Q} = \frac{10336}{162}\)

\(h_{Q} \approxeq 63.8cm = 638mm\)

When the object is placed between the optical centre of the lens and the focal length, the image formed is virtual, erect and magnified.