How does brush placement control the speed of a permanent magnet windshield wiper motor?

What will be an ideal response?


The placement of the brushes determines how many armature windings are connected in the circuit. High speed uses fewer armature windings resulting in less counter electromotive force (CEMF) and greater armature current.

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To reduce heat transfer losses through a glass window, you consider replacing the window with one of three alternatives: a sheet of tin 0.50-cm thick, a layer of brick 8.0- cm thick, and a combination of wood and insulation 4.0-cm thick. The original thickness of the glass is 1.0-cm. Consider the thermal conductivities of each to be the following: glass – 1.40 W/m-K; tin – 66.6 W/m-K; brick – 1.20 W/m-K; wood/insulation combination – 0.09 W/m-K. Considering the inside temperature of the surface to be 20.0°C, and the outside temperature to be -5.0°C, determine the heat conduction rate per unit area for the glass and the three alternatives, and discuss the relative merits of the three alternatives (ignoring material and installation costs).

Given: Ti = 20.0°C; To = -5.0°C What will be an ideal response?

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Where are shorting bars used?

A) In the airbag controller B) In the crash sensors C) At the connectors for airbags D) In pretensioners

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An oil slinger is used with reciprocating compressors that are lubricated by:

A) Both splash and pressure lubrication. B) Pressure lubrication. C) Splash lubrication. D) Oil slingers are only used with scroll compressors.

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A circuit has a source voltage of 50V and a current of 10A. What is the power in watts?