Explanation:
Electromagnetic waves are the waves which are created as the result of the electrical waves which are perpendicular to each other and also perpendicular to the direction of propagation.
Electromagnetic spectrum is range of the frequencies and their respective wavelengths of the various type of the electromagnetic radiation.
In order of the increasing frequency and the photon energy and the decreasing wavelength the spectrum are:
radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
The energy of the radio waves photons is the lowest of all the other waves in the electromagnetic spectrum.
Also, 
Where,
h is Plank's constant having value 
Thus, energy is directly proportional to the frequency. The radio waves have the lowest frequency.
The velocity of the tip of the second hand is 0.0158 m/s
Explanation:
First of all, we need to calculate the angular velocity of the second hand.
We know that the second hand completes one full circle in
T = 60 seconds
Therefore, its angular velocity is:
Now we can calculate the velocity of a point on the tip of the hand by using the formula
where
is the angular velocity
r = 15 cm = 0.15 m is the radius of the circle (the distance of the point from the centre of rotation)
Substituting,
Learn more about angular motion here:
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Density applies to many if not all aspects of life. With density you can explain why ice floats. You can explain why oxygen is on the earth, and not floating around in space( or being replaced by another gas). You can also explain why heat rises while cold air sinks.
A contact force is a type of force which act on an object by coming in contact with the object. Examples of contact force that acts through a force field are: applied force, frictional force, air resistance force, tension, spring force, etc.
Examples of forces that act through a force field are gravitational force, electromagnetic force, the weak interaction and the strong interaction.
<span>The multiple reflection of a single sound wave is echo</span>
