A student makes four resistors using different pieces of wire. The wires have different diameters and lengths. All the pieces of wire are made of the same material. Which piece of wire will make the resistor with the smallest resistance?
diameter 0.5 mm0.5\text{ mm}0.5 mm, length 20 cm20\text{ cm}20 cm
diameter 0.5 mm0.5\text{ mm}0.5 mm, length 45 cm45\text{ cm}45 cm
diameter 1.5 mm1.5\text{ mm}1.5 mm, length 20 cm20\text{ cm}20 cm
diameter 1.5 mm1.5\text{ mm}1.5 mm, length 45 cm45\text{ cm}45 cm
132 exam-style questions on CIE IGCSE Physics 4.2.4a Resistance. Each one has a worked solution and a mark scheme showing where the marks go.