An electrostatic paint sprayer is used to paint metal bicycle frames efficiently. The sprayer charges paint droplets as they pass through the nozzle.
State how the structure of an electrical insulator differs from the structure of a conductor.
The handle of the paint sprayer is made of plastic, which is an electrical insulator. Suggest why the handle is made from an insulator.
Explain, in terms of the particles involved, how the paint droplets become negatively charged and the nozzle becomes positively charged.
The sprayer transfers a charge of 7.5×10−3 C7.5 \times 10^{-3}\text{ C}7.5×10−3 C to the bicycle frame in a time of 5.0×10−4 s5.0 \times 10^{-4}\text{ s}5.0×10−4 s.
Calculate the average current of the charged paint droplets during this time.
452 exam-style questions on CIE IGCSE Physics 4.2 Electrical quantities, covering 4.2.1a Positive and negative charge, 4.2.1b Charging by friction and detecting charge, 4.2.1c Electrical conductors and insulators, 4.2.1d Electric fields and electric field patterns, 4.2.2a Electric current, charge and measuring current, 4.2.2b Conduction in metals and the direction of current, 4.2.2c Direct current and alternating current, 4.2.3a Electromotive force, 4.2.3b Potential difference and voltmeters, 4.2.4a Resistance, 4.2.4b Resistance of a metallic wire, 4.2.4c Current–voltage graphs, and 4.2.5 Electrical energy and electrical power. Each one has a worked solution and a mark scheme showing where the marks go.