# Electronics true or false questions

• Femme_physics
In summary, you asked for confirmation on whether your answers were correct or not, and I have provided a summary of the conversation by stating that your answers were correct for questions 1, 3, and 4, while question 2 was not true. I also included some additional information and clarification on the topics discussed.

#### Femme_physics

Gold Member
Can you help confirm whether my answers are correct or not?

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True or False (+answer must be explained)

Question #1:

Ripple is an alternative component of the DC component of an electrical signal

Answer #1: True. A period, accoriding to wiki, is "small unwanted residual periodic variation of the direct current (dc) output of a power supply which has been derived from an alternating current (ac) source."

Question #2:

The saturation current in a transistor is greater than the conductance current

Saturation current = 0
So it can't be greater than the conductance current!
The conductance current is greater than the saturation current.

Question #3: The following amplification of the op-amp is

Af = 1 + R1/R2

http://img833.imageshack.us/img833/3954/noninvert.jpg [Broken]

Since what we have here is a non-inverting op-amp, that's its formula.

Question #4: The duty cycle of the repeating signal is 40%
http://img15.imageshack.us/img15/3328/dutyc.jpg [Broken]

Answer #4: Not true. Duty cycle is measured when there is current, not when there isn't. Therefor, in this case, it's 60%.

6/10 x 100 = 60%

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Femme_physics said:
Can you help confirm whether my answers are correct or not?

I'll give it a try!
Hope it helps.

Femme_physics said:
Question #1:

Ripple is an alternative component of the DC component of an electrical signal

Answer #1: True. A period, accoriding to wiki, is "small unwanted residual periodic variation of the direct current (dc) output of a power supply which has been derived from an alternating current (ac) source."

Good!

Femme_physics said:

Question #2:

The saturation current in a transistor is greater than the conductance current

Saturation current = 0
So it can't be greater than the conductance current!
The conductance current is greater than the saturation current.

I do not know what you mean by "conduction current"...
There's a couple of possibilities.

But saturation current is when the transistor is saturated with so much base current that it can't open any wider.
This is the highest current you can get...

Femme_physics said:

Question #3: The following amplification of the op-amp is

Af = 1 + R1/R2

http://img833.imageshack.us/img833/3954/noninvert.jpg [Broken]

Since what we have here is a non-inverting op-amp, that's its formula.

It is *almost* the formula...
Can you spot the difference?

Femme_physics said:
Question #4: The duty cycle of the repeating signal is 40%
http://img15.imageshack.us/img15/3328/dutyc.jpg [Broken]

Answer #4: Not true. Duty cycle is measured when there is current, not when there isn't. Therefor, in this case, it's 60%.

6/10 x 100 = 60%

Yep!

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I'll give it a try!
Hope it helps.

You, always.

But saturation current is when the transistor is saturated with so much base current that it can't open any wider.
This is the highest current you can get...

Oh, so my bad. Yes, I forgot...it's kinda in the word, "saturated". *smacks forehead*

So, saturated must always be the highest current, therefor it must be higher than the "conductance current" (It's just the direct translation from hebrew)

EDIT: The translation may be "threshold current", am not sure.

It is *almost* the formula...
Can you spot the difference?

Yes, R1 an R2 are opposite in this case. Got it. Thanks!

Glad I got the other 2 right!

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So it's all good now! ;)

Femme_physics said:
EDIT: The translation may be "threshold current", am not sure.

Threshold current sounds a bit like cutoff current.
Remember that that was the opposite from saturation?

From wikipedia:
wikipedia said:
Cutoff: In cutoff, biasing conditions opposite of saturation are present. There is very little current, which corresponds to a logical "off", or an open switch.

Thanks, ILS. my savior..