Question

Calculate the resistance of 1 km long copper wire of radius 1 mm. Resistivity of the copper is 1.72 x 10-8 Ω m.

Answer 1

Length=1 km=1000m

Radius=1 mm=1*10⁻³ m

Resistivity of copper=1.72x10⁻⁸

Resistance=(Resistivity of copper * Length)/(Area)

                 =(Resistivity of copper * Length)/(r²)

Resistance=[1.72*10⁻⁸*1000]/[22/7*(1*10⁻³)²

Resistance=5.5 ohm

hope it helps :)

Answer 2

Answer:

Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres, between the infrared and the ultraviolet.