This physics problem tests your understanding of fundamental physical laws and their applications. The step-by-step solution below breaks down the problem using relevant equations and physical reasoning.
ScanSolve AI Answer
Here are notes based on the objectives for Electrical Energy and Power: • i) Concepts of electrical energy and power & applying expressions to solve problems: Electrical Energy (E)* is the work done by electric current. It is measured in Joules (J). E = VIt = I^2Rt = (V^2)/(R)t Electrical Power (P)* is the rate at which electrical energy is consumed or produced. It is measured in Watts (W). P = VI = I^2R = (V^2)/(R) • ii) Commercial unit of electric energy and power: The commercial unit of electrical energy is the kilowatt-hour (kWh). 1 kWh = 1000 W × 3600 s = 3.6 × 10^6 J Power is typically measured in Watts (W) or kilowatts (kW) for commercial purposes. • iii) Electric power transmission & analyzing how power is transmitted: Electricity is generated at power stations and transmitted over long distances at very high voltages* (e.g., hundreds of kilovolts) to minimize power loss. Step-up transformers* increase the voltage at the power station. Power loss* in transmission cables is given by P_loss = I^2R_cable. By increasing voltage (V), the current (I) for a given power (P=VI) is reduced, significantly decreasing I^2R losses. Step-down transformers* reduce the voltage for distribution to homes and industries for safety and usability. • iv) Heating effects of electric current & its uses: The heating effect of electric current* (Joule heating) occurs when current flows through a resistor, converting electrical energy into heat energy. The heat produced is H = I^2Rt. Uses:* Electric heaters, toasters, kettles, electric irons, incandescent light bulbs, and fuses. • v) Electrical wiring of houses & advantages of parallel arrangement over series: Houses are wired in a parallel arrangement*. Advantages of parallel wiring:* • Each appliance receives the full supply voltage. • Appliances can be switched on and off independently. • If one appliance fails, others continue to operate. Disadvantages of series wiring:* Appliances would not receive full voltage, could not be operated independently, and the failure of one would break the entire circuit. • vi) Use of fuses & determining the fuse rating: A fuse* is a safety device that protects electrical circuits and appliances from overcurrent. It contains a thin wire that melts and breaks the circuit if the current exceeds a safe limit. The fuse rating* is the maximum current a fuse can carry continuously without melting. To determine the fuse rating for an appliance, calculate its normal operating current using the formula I = (P)/(V), where P is the power of the appliance and V is the supply voltage. The fuse rating should be slightly higher than this calculated current. For example, a 2400 W appliance on a 240 V supply draws I = 2400 W240 V = 10 A. A 13 A fuse would be appropriate.