Answer
D.Diffraction
Explanation
Diffraction is a property that is experienced by waves when they come across a barrier when they are in motion.
The ways tends to curve behind the barrier. This is called diffraction of waves.
Now, sound is a wave and it also experience diffraction. . So the brother will be able to hear the sound due to diffraction
The law of superposition helps scientists determine the relative age of a layer of sedimentary rock. the law of superposition is <span>a basic </span>law<span> of geochronology, stating that in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom, each layer being younger than the one beneath it and older than the one above it</span> .
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Answer:
Light of a shorter wavelength should be used.
Explanation:
This is studied in the phenomenon called photoelectric effect, in which light is able to release electrons from a metal, said electrons are called photoelectrons .
The experiments that have been carried out show that <u>increasing or decreasing the intensity of the light will not cause the photoelectrons to be emitted</u>, what will cause the photoelectrons to be emitted is to increase the frequency of the incident light.
And a higher frequency corresponds to a shorter wavelength according to the equation:

(where
is frequency,
the speed of light, and
the wavelength)
So the answer is that the wavelength of the light must be shortened to cause the emission of electrones.