Answer:

Explanation:
Frequency of each electromagnetic wave is same thus we can interfere them along X axis in Phase diagram.
In phase diagram indicate each wave as vector with amplitude as length and phase difference as angle. (shown in attachment)
Now take component of E2 and E3 amplitude along X direction.
Net amplitude of all E in X direction =
+ cos(45)[
+
]
⇒
Final resultant have no change in frequency
So , resultant is 
<span> In radioactive decay, an unstable atomic nucleus emits particles or radiation and converts to a different atomic nucleus. If the new nucleus is unstable, it will decay again, until eventually, a stable nucleus is formed. Such a sequence of nuclear decays forms a decay series.
The half-life of a radioactive substance is the time required for half of the atoms of a radioactive isotope to decay. If you have, say, 1 million atoms of a specific isotope in a sample, the time required for 500,000 of those atoms to decay is the half-life of that specific isotope. If you have 50 atoms of that isotope, 25 atoms will decay in the same amount of time.
Because the half-life is fixed for a specific isotope, it can be used to date objects. You compare the decay rate of an old object with the decay rate of a fresh sample. Nuclear decay is a first-order process and can be described by a specific mathematical equation, which depends on the decay rate and the half-life. Knowing those values, you can work back and determine the age of an object, as compared with a standard sample. Old objects will not have as much of a radioactive isotope in them as new objects, since the isotopes will have decayed over time in the old object.</span>
Answer:
(i) 
(ii) 
Explanation:
Let t be the average thickness of the sheet.
Given that:
Density of the aluminum sheet is 
Mass of sheet = 60.7 g
Length of sheet = 50.0 cm
Width of sheet = 30.0 cm
(i) Using, Density=Mass/Volume


Hence, the volume of the sheet is
.
(ii) Now, as this aluminum sheet is in the shape of a cuboid, so the volume of the sheet is



Hence, the average thickness of the sheet is
.
Line - A: (15/10) = 1.5 inch/second
Line - B: (0/10) = 0
Line - C: (10/10) = 1.0 inch/second
Line - D: (-25/20) = -1.25 inch/second
<em>Line-A</em> represents the greatest speed.