Rheostat wire is commonly made of alloys like manganin (or nichrome) because of stable resistance and suitable resistivity.

Using higher voltage reduces current for the same power, reducing I^2R transmission losses, so less power is wasted.

Supply voltage = lamp voltage + I·R = 42 V + 10 A × 8.5 Ω = 42 + 85 = 127 V.

Resistance depends on the material (nature) and dimensions (length and cross-sectional area) of the conductor.

In common-base, α = Ic/Ie, so ΔIc = α·ΔIe = 0.9 × 5 mA = 4.5 mA.

Compute resistances R1=200Ω, R2=400Ω; series current = 200/(600)=1/3 A; total power = V×I =200×(1/3)=66.7 W.

A gas diode includes an anode, a cathode and the gas in the tube, so 'All of these' is the complete description.

Multi-range ammeters typically use different low-value shunt resistances in parallel with the galvanometer to measure different current ranges.

Resistance between opposite faces of a square plate is proportional to length/area and cancels side length, so both squares have equal resistance; ratio = 1.

Ohm's law: I = V/R = 2.5 V / 5 Ω = 0.5 A.