GAQM CDCS-001 Certified Data Centre Specialist (CDCS) Exam Practice Test

Standby power, also known as backup power, is a type of power that can be a source available to the data center that takes over the function of supplying when utility power is unavailable. Standby power systems are designed to provide power to critical loads in the event of a power outage, and can include generators, uninterruptible power supplies (UPS), and batteries. Standby power systems can be used to provide power to the data center for a short period of time, such as a few hours or days, until utility power is restored.

Passive, Active and Alternate are not specific type of power sources used in data center. They are terms used in different context and have different meaning.

An ampere (A) is the unit of measurement for electric current. It measures the amount of electrical current flowing through a circuit during a specific time interval. The ampere is named after André-Marie Ampère, a French mathematician and physicist who was one of the main discoverers of electromagnetism.

Ohm (Ω) is the unit of measurement for electric resistance, which is the opposition to the flow of an electric current through a circuit.

Volt (V) is the unit of measurement for electric potential difference, which is the energy required per unit charge to move a test charge between two places in a static electric field.

Watt (W) is the unit of measurement for power, which is the rate at which energy is used or generated in an electrical circuit.

References:

• "Current" (https://www.britannica.com/topic/current-electricity)
• "Electric current" (https://www.sciencedirect.com/topics/engineering/electric-current)
• "Units of Measurement" (https://www.allaboutcircuits.com/textbook/direct-current/chpt-1/units-of-measurement/)

Magnetic circuit breakers use an electromagnetic coil to pull a switch when a circuit carries too much current, thus tripping the circuit and preventing it from exceeding its rated amperage. 

A contactless smart card is a physical security device that uses radio frequency identification (RFID) technology to identify and authenticate an individual. This type of card is used in a variety of applications, such as access control systems and digital payment systems. It is also used in physical access control systems, where the card is used to unlock doors or grant access to restricted areas. Contactless smart cards are also used in building access systems, where the card is used to grant access to certain areas of the building.