Answer:
32.6mm
Explanation:
Using area of a sphere(bulb) = 4πr²
So A is proportional to radius²
So the Energy will be proportional to r²
But 120/80 = 1.5 is the energy factor so
Using
1.5/d² = 1/r²
1.5/40²= 1/r^2
r = √( 40²/ 1.5)
r = 32.6m
Answer:

Explanation:
From the question we are told that
Distance b/e antenna's 
Frequency of antenna Radiation
Distance from receiver 
Intensity of Receiver 
Distance difference of the receiver b/w antenna's 
Generally the equation for Phase difference
is mathematically given by



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Therefore phase difference f between the two radio waves produced by this path difference is given as

Answer:
Transverse
Explanation:
There are two types of waves, according to the direction of their oscillation:
- Transverse waves: in a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. Examples of transverse waves are electromagnetic waves
- Longitudinal waves: in a longitudinal wave, the direction of the oscillation is parallel to the direction of motion of the wave. Examples of longitudinal waves are sound waves.
Light waves corresponds to the visible part of the electromagnetic spectrum, which includes all the different types of electromagnetic waves (which consist of oscillations of electric and magnetic fields that are perpendicular to the direction of propagation of the wave): therefore, they are transverse waves.
<h3><u>Answer;</u></h3>
D) Standing wave
<h3><u>Explanation;</u></h3>
- Standing wave also called stationary wave is a wave which oscillates in time but whose peak amplitude profile does not move in space.
- A standing wave pattern is a vibrational pattern created within a medium when the vibrational frequency of the source causes reflected waves from one end of the medium to interfere with incident waves from the source.
- Examples of standing waves include the vibration of a violin string and electron orbitals in an atom.