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

Wavelength is a measure of the distance that a signal's energy can travel in the time it takes for one cycle of the signal to occur. It is calculated by dividing the speed of light by the frequency of the signal. Wavelength is generally expressed in meters (m). 

 Whenever electrical power is being consumed in an IT room or data center, heat is generated. This heat must be removed in order to maintain an optimal temperature for the equipment, and this is usually done through cooling systems such as air conditioning, air economization, liquid cooling, evaporative cooling, and immersion cooling.

Water cooled systems introduce an additional source of liquid, which can be a potential source of contamination and damage to the IT equipment. Additionally, water cooled systems require more maintenance than air cooled systems and are more expensive to install due to the additional cost of the cooling tower, piping, and pumps.

Ohm (Ω) describes the amount of resistance electricity encounters. It is one of the base units of the International System of Units (SI), and is defined as the amount of resistance that a conductor has when a force of one volt is applied across it. Ohms are used to measure the electrical resistance of a circuit, and can be used to determine the power of a circuit or the amount of current flowing through it.

Convenience outlets, also known as duplex receptacles or wall outlets, are used to provide power to non-computing devices, such as lamps, televisions, and other household appliances. They are typically found in residential and commercial buildings and are connected to a circuit breaker or fuse for protection against overloading and electrical fires

Direct Current (DC) is essential for the process of electrolysis. Electrolysis is the process of breaking down a compound using an electric current. The electric current causes ions to move, which results in a chemical reaction that breaks down the compound. In order for electrolysis to work, a direct current is required, as the ions must flow in one direction. Alternating Current (AC) changes direction and would not provide a consistent flow of ions.

Heating, lighting, and turning a motor can be done by either DC or AC. Heating can be done by passing an electric current through a heating element, which can be powered by either DC or AC. Lighting can be done by passing an electric current through a light bulb, which can be powered by either DC or AC. A motor can be powered by either DC or AC, but the type of motor and the application will determine which type of current is more suitable.

A circuit breaker is a device designed to protect electrical equipment from damage caused by overload or short circuit. Circuit breakers are designed to detect when too much current is flowing through a circuit and to shut the circuit off when that happens. This protects the equipment from damage due to overloading or short circuiting, and it also helps prevent fires and other accidents.

Fuel availability generally dictates the type of standby generator selected as different types of generators use different types of fuel. For example, gasoline generators are typically used in residential or small commercial applications, while diesel generators are usually used in larger industrial and commercial applications. Propane or natural gas generators may also be used, depending on the availability of fuel sources.

The return system in an air distribution system takes the hot exhaust air from the IT equipment and returns it to the Computer Room Air Conditioner (CRAC) unit. The CRAC unit cools the hot exhaust air and recirculates it back into the data center. The return system typically includes ducts, grills, and other components that allow the hot air to be efficiently and effectively returned to the CRAC unit.

Supply system is responsible for bringing in the cooled and filtered air from the CRAC unit to the data center.

Maintenance system and regulation system are not related to air distribution system in the data center.

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.

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. 

AC can be transformed from a low voltage to a high voltage and back again with a transformer, while DC cannot. This makes it easier to distribute AC electricity over long distances and is why it is used more widely than DC electricity. A and B are also true, as wires carrying AC can be bare and don't need to be totally insulated. Wires have less resistance when carrying AC electricity, which is why it is more efficient than DC.