Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

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Fig 27-CO, p.831
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Transcript of Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Page 1: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Fig 27-CO, p.831

Page 2: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Chapter 27: Current and Resistance

27.1 Electric Current

Page 3: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.
Page 4: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.
Page 5: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

CT1: Which current is highest?

CT2: Which current is lowest?

CT3: Is current

A. a vector

B. a scalar

C. neither

P27.9 (p.769)

Page 6: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Chapter 27: Current and Resistance

27.2 Resistance

R = V/I in Ohms ()

Page 7: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

CT4: Suppose a current carrying ohmic metal wire has a cross-sectional area that gradually becomes smaller from one end to the other. Conservation of charge dictates that the current must have the same value throughout the wire. As the area of the wire becomes smaller the

A. drift velocity decreases and resistance per

length increases.

B. drift velocity and resistance per length both

decrease.

C. drift velocity and resistance per length both

increase.

D. drift velocity increases and resistance per

length decreases.

Page 8: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

CT5: A cylindrical wire has a radius r and length l. If both r and l are doubled, the resistance will

A. remain the same.

B. double.

C. quadruple.

D. halve.

E. quarter.

l

r

Page 9: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

R = V/I

R = l/A

P27.11 (p.769)

Page 10: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Histrogram for PHYS202 Exam 1 Spring 2008Average = 50 Low = 20 High = 75

0

1

2

3

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7

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9

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0s 10s 20s 30s 40s 50s 60s 70s 80s 90s

Grade Bin

Nu

mb

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rad

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Page 11: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Histrogram for PHYS202 Total 1 Spring 2008Average = 55 Low = 16 High = 76

0

1

2

3

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0s 10s 20s 30s 40s 50s 60s 70s 80s 90s

Grade Bin

Nu

mb

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in G

rad

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Page 12: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Fig 27-7b, p.838

Page 13: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

= 0[1+(T – T0)]

R = R0[1+(T – T0)]

0 and R0 are at T0

T = temperature

= temperature coefficient of resistance

P27.20 (p.770)

Chapter 27: Current and Resistance

27.4 Resistance and Temperature

Page 14: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Fig 27-11, p.844

Page 15: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Fig 27-10, p.844

Page 16: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Fig 27-12, p.844

Page 17: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

CT6: The current at c is

A. greater than that at d.

B. less than that at d.

C. equal to that at d.

Page 18: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

Imagine bringing dq through any circuit element in time dt

dU = dqV

Power = P = dU/dt = (dq/dt)V

P = IV

P27.26 (p.770)

Chapter 27: Current and Resistance

27.6 Electrical Power

Page 19: Fig 27-CO, p.831. Chapter 27: Current and Resistance 27.1 Electric Current.

CT7: The rank order in current from greatest to least is

A. ace.

B. aec.

C. cea.

D. cae.

E. eca.

F. eac.