The simple harmonic motion not only describes circular movements, also describes waves motion. This makes it fundamental for physics, make us understand waves like sound or light which explains an enormus part of our environment
Answer:
3) Dims in, Brightens out
Explanation:
The relationship between the inductance of a coil and the current is inverse.
As the rod is thrusted into the solenoid, the inductance increases, which in turn decreases the current and the bulb gets dimmer. This is also because some magnetic force is drawn away from the solenoid and the battery.
When the rod is removed, the inductance of the solenoid decreases, the current increases, and the bulb becomes brighter.
Answer: 
Explanation:
Given
Cross-sectional area of wire 
Extension of wire 
Extension in a wire is given by

where, 

for same force, length and material

Divide (i) and (ii)

Answer:
Utilization, effects
Explanation:
The conductors that carry the current to electrical devices and utilization equipment are the heart of all electrical systems. There are associated effects whenever current flows through a conductor.