Answer:
Refracted rays travel through a boundary into a new medium.
Explanation:
Refracted rays travel through a boundary into a new medium. is only true for refraction.
The angle of incidence is the same for angle of refraction, is not true for refraction. Refraction follows Snell's law, states that ratio of the sine of the angle of refraction and the sine of the angle of incidence is always constant and equivalent to the ratio of phase velocities of the two mediums it is passing through.
Refracted rays change direction and go back to the original medium is false for refraction however, it is true for reflection.
Answer:
c. The group speed is less than the phase speed.
Explanation:
For an individual the speed is given by v phase = w/k
w is angular frequency and k is wave number.
This is called phase speed. Group speed is the speed of wave packet.The rate of advance of a crest on a single wave point which is fixed phase.
To answer this question, we must use the equation for the volumetric expansion of gases at constant pressure. This equation is given by:
We know:
is the initial volume 
ΔT is the temperature change = 45 ° -20 ° = 25 °
is the coefficient of gas expansion and is equal to 1/273
Then the final volume of the gas is:
Increased food production due to improved agricultural practices, control of many diseases by modern medicine and the use of energy to make historically uninhabitable areas of Earth inhabitable are examples of things which can extend carrying capacity.
Answer:
The primary reason of seeing the cracker burst and hearing the sound later is because the speed of sound and light. Speed of light is in the vicinity of 3*10^8m,/ sec while the speed of sound is at a distance of 332m/sec. It is similar to lightning that strikes before the sound.
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