Test: Household Circuits - Class 10 MCQ

The relationship is defined by the formula P = VI, where P is power in watts, V is voltage in volts, and I is current in amperes. This equation is fundamental in understanding how electrical power is consumed in circuits.

A switch serves to control the flow of current in an electrical circuit by either allowing it to pass or interrupting it. This on/off functionality is crucial for operating electrical devices safely and efficiently.

The earth pin in a three-pin plug is designed to ensure safety by grounding the appliance. If a fault occurs, it provides a path for excess current to safely dissipate into the ground, reducing the risk of electric shock.

One major advantage of the ring system is that each appliance can have its own fuse, which ensures that if a fault occurs and the fuse blows, it will only affect that appliance and not disrupt the entire circuit. This enhances safety and convenience in household wiring.

The heating effect of electric current is directly proportional to the square of the current flowing through a conductor, as described by Joule's law (H ∝ I^2). This means that as the current increases, the heat produced increases exponentially, which is important for understanding how to manage heat in electrical circuits.

The current rating of a fuse is calculated based on the total power of the appliances in the circuit divided by the voltage of the supply. This ensures that the fuse can adequately protect against overcurrent situations without being too sensitive.

The statement that the tree system is more efficient than the ring system is NOT true. The tree system has several disadvantages, including the requirement for different plugs and sockets, higher installation costs, and the risk of disconnecting all appliances if one fuse blows.

Poor insulation of electrical wires poses a significant danger of electric shock. If the insulation is compromised, it can expose live wires, and touching them can lead to severe injuries or even fatalities.

Earthing, or grounding, refers to connecting an electrical appliance to the ground, providing a safe path for excess current to flow into the earth. This is crucial for preventing electric shock and reducing the risk of fire hazards in electrical circuits.

If the voltage is increased while keeping the power constant, the current must decrease. This relationship is derived from the formula P = VI, where power (P) is the product of voltage (V) and current (I). Thus, increasing V necessitates a decrease in I to maintain constant power.

Increasing the length of a wire increases its resistance. This is because resistance is directly proportional to the length of the conductor; as the path for the current becomes longer, it encounters more resistance, which can affect the overall efficiency of the electrical circuit.

The primary purpose of a fuse is to limit the current in an electric circuit. It protects the circuit by melting and breaking the connection when the current exceeds a specified limit, preventing damage to appliances.

The neutral wire serves the purpose of returning current back to the power source after it has passed through the electrical appliances. It completes the circuit and is essential for the proper functioning of the electrical system.

The watt-hour (Wh) is a commercial unit of energy, commonly used to measure electrical energy consumption. One watt-hour is the energy consumed when a power of one watt is used for one hour.

The resistance of the filament of the bulb can be calculated using the formula R = V^2/P, where V is the voltage rating and P is the power rating of the bulb. This relationship is crucial for ensuring that bulbs operate safely within their specified limits.

When appliances are connected in series, they share the same current. This means that if one appliance fails or is turned off, the entire circuit is broken, resulting in all appliances being inoperable. This is a significant drawback compared to parallel connections.

The SI unit of power is the watt (W), which is defined as one joule per second (J/s). This unit measures the rate at which energy is transferred or converted, making it essential in both electrical and mechanical systems.

Miniature Circuit Breakers (MCBs) are designed to switch off an electrical circuit in a very short duration (approximately 25 milliseconds), providing better protection than traditional fuses. They can be easily reset after addressing the fault, enhancing convenience and safety.

A dual control switch is used to control an appliance from two different locations. This is particularly useful in settings like staircases or long corridors, enhancing convenience and accessibility.

The work done (W) is calculated using the formula W = QV, where Q is the charge in coulombs and V is the potential difference in volts. This relationship highlights that one joule of work is done for every coulomb of charge flowing through a one-volt potential difference.