Question 124: AC fundamentals

Question

In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value :

Accepted Answer

$${\omega } = {1 \over {\sqrt {LC} }}$$
$$ \Rightarrow $$ 2$$\pi $$f = $${1 \over {\sqrt {LC} }}$$
$$ \Rightarrow $$ f = $${1 \over {2\pi \sqrt {LC} }}$$
f does not depends on resistance(R).
Quality factor, $$Q = {{\omega L} \over R}$$
$$ \Rightarrow $$ $$Q \propto {1 \over R}$$
So if R increase then Q will decrease.
Also, $$Q = {{\omega L} \over R} = {\omega  \over {\Delta \beta}}$$
where $$\Delta \beta$$ = bandwidth
$$\Delta \beta  = {R \over L}$$
So if R increase then $$\Delta \beta$$ will increase too.

Answer

The bandwidth of resonance circuit will increase.

Answer

The resonance frequency will increase.

Answer

The quality factor will increase.

Answer

The quality factor and the resonance frequency will remain constant.

AC fundamentals

In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value :

Choose the correct answer: