LF2

1. A: A number system is used to represent numbers according to specific rules, where each digit's value depends on its position in the number. Most number systems are positional systems, where each position represents a power of the base.

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1. A: The Decimal system has a base of 10 and uses the digits 0 through 9.

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1. A: The Binary system has a base of 2 and uses only the digits 0 and 1. It is important in computing because it represents the smallest unit of information (a bit), which can stand for "on/off," "yes/no," or "true/false."

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1. A: The Hexadecimal system has a base of 16 and uses digits 0-9 and letters A-F. It is used in computing because it simplifies the representation of binary data, as one hexadecimal digit corresponds to 4 bits.

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A: In a positional number system, the value of a digit depends on its position, with each position representing a power of the base. For example, in the Decimal system, the rightmost digit represents 100 (ones), the next 101101 (tens), and so on

A: The Octal system has a base of 8 and uses digits 0 through 7.

A: An electrical layperson is someone without formal qualifications in electrical work. They are only allowed to perform basic tasks like plugging in devices or changing light bulbs.

1. A: Low voltage in households is defined as up to 1000 volts AC.

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1. A: An RCD detects when less current returns through the neutral wire than flows through the live wire, indicating a fault (e.g., a short circuit or leakage). It quickly disconnects the circuit to prevent electric shock.

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1. Disconnect the power.

2. Secure against reconnection.

3. Verify the absence of voltage.

4. Ground and short-circuit.

5. Cover or shield adjacent live parts.

A: The live wire carries current from the power source to the device, while the neutral wire completes the circuit by returning current to the source. The neutral wire is at ground potential.

A: Multiple extension cords can overload the circuit, causing overheating and potentially leading to fires. They also reduce the effectiveness of safety devices like circuit breakers.

A: A UPS provides backup power to connected devices when the main power supply fails or drops below a critical voltage level.

1. Standby (VFD): Switches to battery power only during a power failure.

2. Line Interactive (VI): Corrects minor voltage fluctuations without switching to battery.

3. Online (VFI): Continuously powers devices from the battery, isolating them from the main power supply.

A: The inverter converts the DC power from the battery into AC power to supply connected devices during a power outage.

A: The switching time is typically 4 to 10 milliseconds, which is within the hold-up time of most ATX power supplies (16 ms).

A: A standby UPS only activates the battery during a power failure, while an online UPS continuously powers devices from the battery, providing complete isolation from the main power supply.

A: Sine wave inverters produce a cleaner, smoother AC output, which is necessary for sensitive equipment. Square wave inverters are simpler and cheaper but are not suitable for all devices.