3.8 Power Flashcards
(33 cards)
What is the definition of electrical power?
The rate at which work is done or heat is transferred
What is kinetic energy?
Energy stored in a moving body
What is potential energy?
The energy stored by a system which may later be transferred to another energy store
Energy transfers are classified as either?
Heat or work
When is heat transferred?
When thermal energy moves from a region of higher temperature to a region of lower temperature
What is work in electrical systems?
The energy transferred when an electric charge is moved between two points in a circuit
Work done is measured in?
Joules (J)
What does one joule equate to?
The amount of work done when a charge of one coulomb is moved through a potential difference of one volt
What is potential difference measure in?
Volts
The rate of power equation is?
Change in quantity divided by the time taken for it to change
What is power measured in?
Joules per second (j/s)
What is joules per second also known as?
Watts (W)
What is electrical power?
The number of joules of energy transferred to or from a circuit in one second
What is electrical power measured in?
Joules per second (J/s) or watts (W)
For alternating current devices does the power vary overtime or stay the same?
It varies over time
For direct current devices does the power vary overtime or stay the same?
It stays the same
What are the two ways of measuring electrical power?
-using a wattmeter
-using a voltmeter and a ammeter then calculating manually
What is a wattmeter?
A special meter that consists of a voltmeter and an ammeter which calculates for you
What are the units of a wattmeter?
Watts
A wattmeter is know to take a _____ measurement of power?
Direct
Measuring voltage and current with a voltmeter and ammeter to find out the power is known as?
An indirect measurement of power
A voltmeter measures two points in a circuit by measuring?
In parallel
An ammeter is connected in _____ to measure current?
Series
The rate at which heat is dissipated is also known as?
Power (P)
