Understanding Phase Change: R, L & C

Click For Summary
Phase change is crucial in electrical systems because it highlights the differences in voltage and current across resistors (R), inductors (L), and capacitors (C). Complex impedances inherently cause a phase shift between the applied voltage and the resulting current. Specifically, in an inductor, the current lags behind the voltage, illustrating this phase relationship. Understanding these phase shifts is essential for accurately analyzing complex impedance problems. Thus, recognizing phase change is fundamental for effective circuit analysis and design.
hidemi
Messages
206
Reaction score
36
Homework Statement
If the input to an RLC series circuit is V = Vm Cos ωt, then the current in the circuit is?
The answer is (D) as attached.
Relevant Equations
V = IZ
Z = [ R^2 + (XL - Xc)^2]^1/2
Why do we need to consider phase change?
Here are my thoughts: is it because voltages are different in phase for each of the three electrical accessories, R, L and C?
 

Attachments

  • 1.jpg
    1.jpg
    33.2 KB · Views: 316
Physics news on Phys.org
Because complex impedances will, in general, cause a phase shift between the voltage applied and the current. It's what they do. Suppose Z is just an inductor, would the current be in phase with the voltage?
 
DaveE said:
Because complex impedances will, in general, cause a phase shift between the voltage applied and the current. It's what they do. Suppose Z is just an inductor, would the current be in phase with the voltage?
No, the current will be lagged after voltage.
 
hidemi said:
No, the current will be lagged after voltage.
Which will appear as a phase shift between the voltage and current. That is why phase matters for complex impedance problems.
 
DaveE said:
Which will appear as a phase shift between the voltage and current. That is why phase matters for complex impedance problems.
Thank you for your further explanation.
 
Thread 'Chain falling out of a horizontal tube onto a table'

Thread 'Chain falling out of a horizontal tube onto a table'

My attempt: Initial total M.E = PE of hanging part + PE of part of chain in the tube. I've considered the table as to be at zero of PE. PE of hanging part = ##\frac{1}{2} \frac{m}{l}gh^{2}##. PE of part in the tube = ##\frac{m}{l}(l - h)gh##. Final ME = ##\frac{1}{2}\frac{m}{l}gh^{2}## + ##\frac{1}{2}\frac{m}{l}hv^{2}##. Since Initial ME = Final ME. Therefore, ##\frac{1}{2}\frac{m}{l}hv^{2}## = ##\frac{m}{l}(l-h)gh##. Solving this gives: ## v = \sqrt{2g(l-h)}##. But the answer in the book...
View full post »

Similar threads

How Does Loudspeaker Movement Affect the Phase of Reflected Waves?
  • · Replies 3 ·
Replies
3
Views
1K
Finding equilibrium temperature when there are phase changes
  • · Replies 2 ·
Replies
2
Views
1K
How Does Changing Distance Affect Microwave Path Difference?
  • · Replies 7 ·
Replies
7
Views
961
Handling two SHMs in different directions
  • · Replies 18 ·
Replies
18
Views
975
Contradiction in Phase of reflected sound
  • · Replies 1 ·
Replies
1
Views
1K
Focussing a collimated beam using a diffraction grating
  • · Replies 1 ·
Replies
1
Views
745
Calculation of current in driven series RLC circuit
  • · Replies 8 ·
Replies
8
Views
2K
Is Reflection of an Incident Wave Lagging or Advancing?
  • · Replies 1 ·
Replies
1
Views
1K
Air wedge - why is reflection from top of first slide ignored?
  • · Replies 1 ·
Replies
1
Views
1K
Combined tensions of an RLC series circuit with AC current
  • · Replies 3 ·
Replies
3
Views
935