An electric heater uses a resistance wire of resistance 24 Ω24\ \Omega24 Ω. The power dissipated in the resistance wire is 2200 W2200\text{ W}2200 W.
Calculate the current in the resistance wire.
The resistance wire of the heater has a length of 1.6 m1.6\text{ m}1.6 m and a cross-sectional area of 6.0×10−7 m26.0 \times 10^{-7}\text{ m}^26.0×10−7 m2.
A new heater is designed using wire of the same material with length 2.4 m2.4\text{ m}2.4 m and cross-sectional area 4.5×10−7 m24.5 \times 10^{-7}\text{ m}^24.5×10−7 m2.
Calculate the resistance of this wire.
The 2200 W2200\text{ W}2200 W heater is used in a country where electricity costs 0.250.250.25 dollars per kilowatt-hour.
Calculate the cost of using the heater continuously for three days.
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.