Microwaves are transmitted by Radio Waves.
Answer:

Explanation:
Refractive Index: It is a measure to find how fast the light travels through a medium. It is ration of the speed of light in vacuum to speed of light in the medium. Speed of light is not constant and varies depending on the density of the medium.
In vacuum the speed of light is 300000 km/s and is denoted by c. When the light beam enters any medium the speed will decrease. Here it is given that the speed in plastic is v. Thus the refractive index(n) is given as:

It is a dimensionless no.
Answer: Option (d) is correct.
Explanation:
Given, 1,152 British thermal units
1 British thermal unit = 1055.06 joules
So, in 1,152 British thermal units there will be :

Hence, from the given options the closest answer is of option (d). So, option (d) is correct.
Answer: The angle of inclination is nearly 30°
Explanation:
For a body on an inclined plane, the coefficient of friction between the body and the plane is equal to the ratio of the moving force applied to the body to the frictional force acting on the body.
If uK coefficient of friction;
Fm is the moving force
R is the normal reaction on the body
Mathematically uK = Fm/R
Fm = WSin(theta)
R = Wcos(theta)
uK = Wsin(theta)/Wcos(theta)
uK = tan(theta)
theta = arctan(uK)
If uK is 0.58
theta = arctan0.58
theta = 30°
The angle of the inclined will be 30°
The number of times a standard quantity is present in the given physical quantity is called magnitude of a physical quantity