Answer:
Periodic.
Explanation:
Electromagnetic waves is a propagating medium used in all communications device to transmit data (messages) from the device of the sender to the device of the receiver.
Generally, the most commonly used electromagnetic wave technology in telecommunications is radio waves.
Radio waves can be defined as an electromagnetic wave that has its frequency ranging from 30 GHz to 300 GHz and its wavelength between 1mm and 3000m. Therefore, radio waves are a series of repetitive valleys and peaks that are typically characterized of having the longest wavelength in the electromagnetic spectrum.
Basically, as a result of radio waves having long wavelengths, they are mainly used in long-distance communications such as the carriage and transmission of data.
Generally, a fixed speed is used for the propagation of traveling waves and this speed is usually denoted with the variable "v" or sometimes "c."
Furthermore, if the waveform of a traveling wave is repeated every time at specific intervals T, it is referred to as periodic wave.
Mathematically, the period of a traveling wave is given by the formula;

Where;
T is the time measured in seconds.
Answer:
400 N
Explanation:
By the law of friction,

is the maximum frictional force,
is the coefficient of friction and
is the reaction on the refrigerator. On a horizontal surface, the reaction is equal to the weight of the refrigerator.


While not moving, the fricition on the refrigerator is static friction. So, 

This is the maximum frictional force and is more than the applied horizontal force of 400 N. Frictional force cannot be more than the applied force, else it would actually pull the refrigerator backwards (a strange thing, if it were to happen). It is equal to the extent of the applied force because the applied force is not enough to overcome the maximum.
Hence the frictional force is 400 N.
PS: Note that we do not use the coefficient of kinetic friction because applied force could not overcome the static friction.
Answer:
0.5849Weber
Explanation:
The formula for calculating the magnetic flus is expressed as:

Given
The magnitude of the magnetic field B = 3.35T
Area of the loop = πr² = 3.14(0.24)² = 0.180864m²
angle of the wire loop θ = 15.1°
Substitute the given values into the formula:

Hence the magnetic flux Φ through the loop is 0.5849Weber