# Rate in the Electrical System by dandanhuanghuang

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• pg 1
```									Rate in the Electrical
System
Unit 3 Sub 3
Rate in the Electrical System
1. What is the prime mover in the electric
system?
- voltage
2. What is electric rate?
- amount of charge that flows through a
conductor in a unit of time
3. What term in given to electric rate?
- current
Rate in the Electrical System
4. What letter is used to represent electric
current?
-I
5. What unit is used to measure current?
- amperes (amps)
Rate in the Electrical System
6. What is the equation for calculating current?
- Current = charge moved
elapsed time
-I=q
t
7. When is electrical current one ampere?
- when one coulomb of charge is moved in
one second
Rate in the Electrical System
8. Example – A DC motor operates at a
rate of 10 amperes for 10 seconds. How
much charge moves through the motor?
-I=q
t
- 10 amps = q
10 sec
- q = 100 coulombs
Rate in the Electrical System
9. What is the difference between AC and
DC current?
- DC current flows only one way – from
the negative electrode to the positive
- AC current flows either way – the
electrons constantly change direction
Rate in the Electrical System
10. Why is AC current used in homes and
- it is much more economical to transfer AC
current over long distances than DC current
11. How do you measure voltage in a circuit?
- voltmeter
- it is connected in parallel with the circuit
Rate in the Electrical System
12. How do you measure current in a
circuit?
- ammeter
- it is connected in series with the circuit
13. What is a VOM?
- a handheld device that measures both
current and voltage
Rate in the Electrical System
14. What is frequency in terms of AC
current?
- measure of how often the current
alternates
15.What unit is used to measure
frequency?
- hertz (Hz) – both SI and English
Rate in the Electrical System
16. How is frequency calculated?
f=n/t
- f = frequency
- n = number of cycles
- t = time
Rate in the Electrical System
17. Example – A generator produces an
electrical signal that has 240 cycles in
4 seconds. What is the frequency of
the signal?
f=n/t
f = 240 cycles / 4 seconds
f = 60 Hz
Rate in the Electrical System
18. How are frequency and period related?
- period is the time it takes for one cycle to
occur
f=1/T
- T = period (usually in seconds)
T=1/f
Rate in the Electrical System
19. Example – The frequency of an electrical
wave is 60 Hz. What is the period of the
wave for one cycle?
-T=1/f
- T = 1 / 60 Hz
- T = 0.0167 sec

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