Answer:A solenoid is a simple electromagnetic device consisting of a coiled electric wire, wrapped in a 3D circular pattern. When electric current is passed through the wire, the solenoid acts like a magnet with N and S poles at the ends of the coil.
When a ferromagnetic material rod is permanently placed inside the solenoid, the metal greatly increases the magnetic effect and becomes a permanent electromagnet. Moreover, it can also be used as an electrical switch by drawing in or pushing out a ferromagnetic material like an iron rod. Depending on the directions of the rod and the electrical current the switching action takes place.
Given figure represents the solenoid as electromagnet and the switching action.
Explanation:
Answer:
ion
Explanation:
when ever an atom or group of atoms get charge they are called ion or ions
The equation for the resistance R is: R=ρ*(l/A), where, ρ is electrical resistivity, l is the length of the conductor, and A is the surface area.
The initial surface area is:
A=r²π, then when we double the radius we get:
A₁=(2*r)²π=4*r²π=4*A
Initial resistance is: R=ρ*(l/A).
When we double the radius, resistance is: R₁=ρ*{ l / (4*A) }
The ratio of the new resistance to the old one:
R₁/R=[ρ*(l/A)] / [ ρ* { l / (4*A) } ] = ρ, l and A cancel out and we get:
R₁/R=(1/1)/(1/4)=4/1
Hi C is the Answer I believe
