PHYSICS 5054 · STRUCTURED PRACTICE
1
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.
Total: 9 marks