Physics 0625 · Question 1[9 marks]
A student investigates the electrical characteristics of metallic wires.
(a)[2]
State Ohm's law and specify the physical condition required for it to hold.
(b)[3]
Sketch I–V graphs on the same axes for
(i)
an Ohmic resistor and
(ii)[3]
a filament lamp.
(c)[4]
Wire X has length 1.2 m, cross-sectional area 0.40 mm², and resistance 6.0 Ω. Wire Y is made of the same metal with length 3.6 m and cross-sectional area 0.80 mm².
(i)[2]
Calculate the resistance of Wire Y.
(ii)[2]
Calculate the current in Wire X when a p.d. of 4.5 V is applied across it.