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Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

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541.

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.

View answer & explanation

Correct answer is A

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.

542.

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

1m; 0.25Hz

2m; 0.25Hz

2m; 0.50Hz

4m; 0.50Hz

View answer & explanation

Correct answer is C

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

543.

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]

41.8°

48.2°

60.8°

90.0°

View answer & explanation

Correct answer is A

$\eta = \frac{1}{sin\theta}$

$1.5 = \frac{1}{sin\theta}$

$sin\theta = \frac{1}{1.5} = 0.667$

$\theta = sin^{-1}(0.667) = 41.835°$

$\approxeq 41.8°$

544.

Plane waves through a narrow gap emerge as circular waves. This phenomenon is known as

interference

dispersion

refraction

diffraction

View answer & explanation

Correct answer is D

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.

545.

Consider the wave equation: $y = 10sin(x - 50t)$ , What does the number 10 represent?

Acceleration

Speed

Amplitude

Wavelength

View answer & explanation

Correct answer is C

Comparing the given equation with the wave equation:

$Asin(kx - \omega t)$ , we have that A = 10 which is the amplitude of the wave.