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Sample Practice Test Questions
What is the primary difference between a rectifier and an inverter?
a rectifier converts an AC input to DC while an inverter converts a DC input to AC
A diode allows current to pass easily in one direction and blocks current in the other direction. Diodes are commonly used for rectification which is the conversion of alternating current (AC) into direct current (DC). Because a diode only allows current flow in one direction, it will pass either the upper or lower half of AC waves (half-wave rectification) creating pulsating DC. Multiple diodes can be connected together to utilize both halves of the AC signal in full-wave rectification.
An element in the physical state of __________ maintains a constant volume and shape.
solid
An element in a solid state has atoms or molecules that are constricted and do not move freely. Solids maintain a constant volume and shape and exist at a lower temperature than liquids or gases.
One of the lights on your Christmas tree burns out and this causes the rest of the lights connected to that strand to go dark. How are the lights in that strand connected?
series
Lights connected in series form a chain with each light connecting to adjacent lights via one wire. Therefore, if one of the lights burns out and breaks the series, none of the other lights will receive power and they'll go dark. Lights connected in parallel each connect to the positive and negative nodes of the power source and would not go dark if one of their neighbors burnt out.
The Earth's rocks fall into three categories based on how they're formed. Which of the following is formed when existing rock is altered through pressure, temperature, or chemical processes?
metamorphic
The Earth's rocks fall into three categories based on how they're formed. Igneous rock (granite, basalt, obsidian) is formed from the hardening of molten rock (lava), sedimentary rock (shale, sandstone, coal) is formed by the gradual despositing and cementing of rock and other debris, and metamorphic rock (marble, slate, quartzite) which is formed when existing rock is altered though pressure, temperature, or chemical processes.
The mechanical advantage of a wheel and axle is equal to the:
ratio of the diameters of the wheels
A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.
Which of the following maintains pressure in the cooling system?
radiator cap
The radiator is responsible for tranferring heat from the coolant to the outside air. Radiator hoses transfer coolant to and from the engine to the radiator and a radiator cap maintains pressure in the cooling system to increase the boiling point of the coolant mixture and thus allow it to absorb more heat.
What type of current flows in only one direction in a circuit?
direct
Direct current flows in only one direction in a circuit, from the negative terminal of the voltage source to the positive. A common source of direct current (DC) is a battery.
The force required to initally get an object moving is __________ the force required to keep it moving.
higher than
For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).