Test: Electricity - Grade 4 MCQ

The primary role of a distribution board is to distribute electricity to different circuits within the house. It ensures that electrical supply is safely routed to various appliances and areas, allowing for independent operation.

Fuse wires are typically made from an alloy of lead and tin. This material has a low melting point, allowing it to melt quickly in the event of excess current, thus protecting the electrical circuit.

A Miniature Circuit Breaker (MCB) automatically switches off the circuit when the current exceeds a safe level. This quick response helps to prevent electrical fires and damage to appliances.

A short circuit occurs when there is an unintended connection between live and neutral wires, allowing a large current to flow. This situation can lead to overheating, appliance damage, and potentially fires, making it a serious electrical hazard.

Electrical energy for billing purposes is typically measured in kilowatt-hours (kWh). This unit quantifies the amount of energy consumed over time, allowing for accurate billing based on usage.

Electrical energy is calculated using the formula Energy = Power × Time. This means the energy consumed is directly proportional to the power rating of the appliance and the duration it is used.

A 15 A fuse has a higher thickness compared to a 5 A fuse, which allows it to safely handle a greater current. This difference in thickness is essential to ensure that the fuse operates within its rated current without melting.

Batteries provide Direct Current (D.C.), which flows in one direction only. This is different from Alternating Current (A.C.), which changes direction periodically. Understanding the difference between D.C. and A.C. is crucial for using electrical devices correctly.

The formula for calculating power in an electrical circuit is Power = Voltage × Current (P = V × I). This relationship shows how power consumption increases with higher voltage or current.

The initial reading of the kWh meter is 5025 kWh. This value represents the total energy consumed up to that point, which is crucial for tracking usage and calculating bills.

An electric fuse acts as a safety device designed to protect circuits from overload. When the current exceeds a safe level, the fuse wire melts, breaking the circuit and preventing potential damage to appliances or electrical fires.

A fuse melts to break the circuit during overload conditions. This action prevents excessive current from damaging appliances or causing electrical fires, making it a crucial safety device in electrical systems.

A kWh meter measures the total energy consumed in kilowatt-hours (kWh). This measurement is crucial for calculating electricity bills, as it reflects the actual usage of electrical energy by various appliances within a household.

The outer body of electrical appliances should be earthed to prevent electric shock. If a fault occurs and the live wire touches the outer body, earthing provides a safe path for the current to flow to the ground, protecting users.

The neutral wire is usually colored black or light blue in household wiring. This color coding helps in safely identifying wires during installation and maintenance.

Ensuring proper earthing is a critical safety precaution when using electrical gadgets. This helps prevent electric shocks by providing a safe path for stray currents, thereby protecting the user and the appliances.

Households in India are typically supplied with 220 V of A.C. This voltage level is standard for most household appliances, ensuring they operate efficiently without damage.

The frequency of A.C. supply in India is 50 Hz. This means that the current changes direction 50 times per second, which is standard for household electrical systems in the country.

Overloading an electrical circuit can lead to a potential fire hazard. When too many devices draw current beyond the circuit's capacity, it can cause overheating, damaging wires and potentially igniting a fire.

The earth wire is designed to protect against electric shocks by providing a safe path for excess current to flow into the ground. This is vital for appliances with metallic bodies, ensuring user safety.