Electricity consumption is measured in kilowatt-hours (kWh), which is a unit of energy. Since power (measured in Watts) multiplied by time equals energy, the billing is based on the total power consumed over a specific duration. Voltage, resistance (Ohm), and current (Ampere) are instantaneous electrical parameters, but the total energy consumed (Watt-hours) is the metric used for billing.
14962
What physical phenomenon causes a fuse in a domestic electrical circuit to melt?
An electric fuse is a safety device designed to protect circuits from overcurrent. When the current flowing through the circuit exceeds the rated capacity of the fuse wire, the heat generated (proportional to the square of the current) causes the wire to melt, thereby breaking the circuit and preventing damage.
14963
What is the phenomenon where a potential difference is generated along a conductor due to a temperature gradient?
The Thomson effect describes the heating or cooling of a current-carrying conductor when a temperature gradient is maintained along it. It is the evolution or absorption of heat when an electric current flows through a conductor across which a temperature difference exists. This is distinct from the Seebeck effect, which involves two different metals, and the Peltier effect, which involves heat transfer at junctions.
14964
If a conductor produces 2000 J of heat with a 1A current, how much heat is produced if the current is doubled?
According to Joule's Law of heating, H = I²Rt. If the current (I) is doubled, the heat produced (H) becomes (2I)² = 4 times the original heat. Therefore, 4 × 2000 J = 8000 J.
14965
When an incandescent light bulb is powered, into which forms of energy is the electrical energy primarily converted?
An incandescent bulb functions by passing current through a filament, which heats up due to resistance. As the filament reaches high temperatures, it emits both thermal radiation (heat) and visible light. While the primary goal is illumination, a significant portion of the electrical energy is dissipated as heat, making the process a conversion into both forms.
14966
What is the formula for the electrical energy supplied by a charge Q over a time interval t?
Electrical energy (E) is defined as the product of power (P) and time (t). Since power in an electrical circuit is the product of voltage (V) and current (I), the energy is calculated as E = P * t = (V * I) * t. This formula represents the total work done by the electric field to move a charge through a potential difference over a specific duration.
14967
Which of the following sequences correctly lists common household appliances in ascending order of their typical power consumption?
Power consumption varies by device. A typical ceiling fan consumes 50-75W, a television 100-150W, an electric iron (press) 1000W, and an electric kettle 1500-2000W. Therefore, the ascending order is Fan < Television < Electronic press < Electronic kettle. Note: The source option C contains a typo 'ketrle' but is the correct sequence.
14968
Which physical effect of electric current is utilized in the operation of a fuse wire to protect electrical circuits?
A fuse wire is designed to melt when the current exceeds a specific threshold. This occurs due to the Joule heating effect (I²Rt), where the electrical energy is converted into thermal energy, causing the wire to reach its melting point and break the circuit.
14969
Which of the following devices is designed to convert chemical energy directly into electrical energy?
An electric cell (or battery) utilizes chemical reactions between its internal components (electrodes and electrolyte) to generate a flow of electrons, thereby converting stored chemical energy into electrical energy. In contrast, heaters, fans, and hair dryers are devices that consume electrical energy to perform work or produce heat.
14970
Regarding the use of a fuse as a safety device in an electrical circuit, which statement is correct?
A fuse is a safety component designed to break the circuit when excessive current flows. It must be connected in series with the load. The critical property of a fuse wire is its low melting point, which allows it to melt and disconnect the circuit quickly when the current exceeds the rated limit, preventing damage to appliances or fire hazards.
