2017 - WAEC Physics Past Questions and Answers - page 3
A vapour whose molecules are in dynamic equilibrium with those of its own liquid is said to be
A saturated vapour is one which is in a dynamic equilibrium with its own liquid.
The diagram above illustrates two waves of equal amplitudes A and frequencies approaching each other. When the two waves meet at a point I midway between them, the vertical displacement of the resulting wave will be
This is a type of constructive interference. When two waves of equal amplitude are interfering constructively, the resulting amplitude is twice as large as the amplitude of an individual wave.
= A + A = 2A
A rainbow is formed when sunlight is incident on water droplets suspended in the air due to
Which of the following statements about the 3rd overtone of a vibrating air column of an open pipe is correct? It has
The 3rd overtone for an open pipe has 5 antinodes and 4 nodes.
Consider the wave equation: \(y = 10sin(x - 50t)\), What does the number 10 represent?
Comparing the given equation with the wave equation:
\(Asin(kx - \omega t)\), we have that A = 10 which is the amplitude of the wave.
Plane waves through a narrow gap emerge as circular waves. This phenomenon is known as
Diffraction refers to the various things that occur when a wave encounters an obstacle. This bending of the wave after it passes a small gap is an example of diffraction.
A ray of light incident at an angle \(\theta\) in a rectangular prism grazes the surface of the prism on emerging from the prism. Determine the value of the angle. [Absolute refractive index of the material of the prism is 1.5]
\(\eta = \frac{1}{sin\theta}\)
\(1.5 = \frac{1}{sin\theta}\)
\(sin\theta = \frac{1}{1.5} = 0.667\)
\(\theta = sin^{-1}(0.667) = 41.835°\)
\(\approxeq 41.8°\)
The diagram above illustrates a wave setup between two fixed ends 4.0m apart. If the speed of the wave is 1.0\(ms^{-1}\), its wavelength and frequency respectively are
For the 4th harmonic, \(L = 2\lambda\)
\(4m = 2\lambda \implies \lambda = \frac{4m}{2}\)
=\(2m\)
Recall, \(v = f\lambda\)
\(1 = f \times 2 \implies f = \frac{1}{2}\)
= 0.50Hz
Two plane mirrors are inclined at an angle 20° to each other. Determine the number of images formed when an object is placed between them.
The number of images formed = \(\frac{360}{n}\) where the value gotten is odd
else, = \(\frac{360}{n} -1\).
Solving, we have that \(\frac{360}{20} = 18\)
Hence, the no of images formed is 18 - 1 = 17.
A converging lens of focal length 10cm forms an erect image three times the size of the real object. Calculate the distance between the image and the object.
Given, image size = 3U
object size = U
focal length = 10cm
lens to object distance = \(\frac{focal length \times object size}{image size}\)
= \(\frac{10 \times u}{3u} = 3.33\)
distance between image and object = 10 + 3.33 = 13.33cm