To calculate energy consumption in kilowatt-hours (kWh), first convert the power rating from watts to kilowatts by dividing by 1000 (400 W = 0.4 kW). Then, multiply the power in kilowatts by the time in hours (0.4 kW * 5 hours = 2 kWh). This calculation shows the total energy used by the appliance over the specified duration.
14722
How many units of electricity are consumed if a 100-watt bulb operates for 10 hours?
One unit of electricity is equivalent to 1 kilowatt-hour (kWh). Calculating the energy consumption: 100 watts = 0.1 kW. Multiplying 0.1 kW by 10 hours results in 1 kWh, which is exactly 1 unit of electricity.
14723
If a household consumes 150 units of electricity in a month, what is this energy equivalent to in joules?
One unit of electricity is 1 kWh. Since 1 kWh = 3.6 × 10^6 joules, 150 units = 150 × 3.6 × 10^6 = 540 × 10^6 = 5.4 × 10^8 joules. This conversion is standard in electrical energy calculations.
14724
Why does the brightness of an incandescent light bulb gradually diminish over its operational lifespan?
Over time, the tungsten filament in an incandescent bulb undergoes sublimation, where metal atoms evaporate from the filament and deposit on the inner surface of the glass bulb. This process thins the filament, increasing its resistance and reducing its light output before eventual failure.
14725
In standard electrical wiring, what is the conventional color coding for the live wire?
According to international electrical standards (such as IEC), the live wire, which carries the current from the power source to the appliance, is typically identified by red or brown insulation to distinguish it from the neutral and earth wires.
14726
Which gases are typically contained within a fluorescent tube to facilitate light emission?
Fluorescent tubes contain a small amount of mercury vapor and an inert gas like neon or argon. When electricity passes through, the mercury vapor emits ultraviolet light, which then excites the phosphor coating to produce visible light.
14727
What form of energy is produced by electric cells and batteries through chemical reactions?
Electric cells and batteries function by converting stored chemical potential energy into electrical energy. While the chemical reaction is the source, the output provided to an external circuit is electrical energy, which drives the flow of charge.
14728
In an electrical circuit, how is a fuse typically connected to the live wire?
A fuse is a safety device designed to break the circuit if the current exceeds a safe limit. It must be connected in series with the live wire so that all current flowing to the appliance passes through it, ensuring it melts and disconnects the supply during an overload.
14729
What is the mathematical expression for the rate at which electrical energy is converted into heat?
The rate of energy conversion is defined as power. According to Joule's Law of heating, the power dissipated as heat in a resistor is given by P = I^2 * R, where I is the current and R is the resistance. The other options represent total energy (work) over time, rather than the rate of conversion (power).
14730
To which part of an electrical appliance is the earth wire of a power cable typically connected?
The earth wire is connected to the metallic casing of an appliance. This safety measure ensures that if a fault occurs and the casing becomes live, the current flows to the ground, preventing electric shock to the user.
