sad electricity.

[physics]

what does a -ve voltage represent in a input voltage graph (sin) graph shape that goes up and down from +10 to -10V ? what does it mean
i'm confused but someone told me it means the current is reversed for a diode or somethin and i dont get how there can be a -ve voltage etc etc.

[physics]

When Vout is 6 V what is the resisitance of the LDR?
i used the vout formula where the v out is 3 and i get 668933ohms which is wrong

[physics]

Can someone help me with what p and n type is? i have no idea.

[physics]

The voltage across the photodiode? shouldnt it be 6V since its in reverse bias and no current hence no volatage can pass to the rresistor anyway :S but the answer is 3.5V

[Chavi]

what does a -ve voltage represent in a input voltage graph (sin) graph shape that goes up and down from +10 to -10V ? what does it mean
i'm confused but someone told me it means the current is reversed for a diode or somethin and i dont get how there can be a -ve voltage etc etc.

Not 100% sure, but I think it has to do with Alternating current (which you then convert to DC by the RMS forumula if you need to)

When Vout is 6 V what is the resisitance of the LDR?
i used the vout formula where the v out is 3 and i get 668933ohms which is wrong

Vout = (r2)/(r2 + r1) x Vin
So, 6 = r2/(r2 + 2000) x 9

Rearranging gives:
6r2 + 12000 = 9r2
so r2 = 4000 ohms

Can someone help me with what p and n type is? i have no idea.

From my basic understanding in trying to decode Heinmann 12, a semiconductor is "doped" (mixed with another element) to create a diode. Depending on the numer of electrons in the added element, the semiconductor will either lack an electron (p type - for overall positive charge) or have an extra electron (n type - overall negative charge).

[the.watchman]

When Vout is 6 V what is the resisitance of the LDR?
i used the vout formula where the v out is 3 and i get 668933ohms which is wrong

Vout = (r2)/(r2 + r1) x Vin
So, 6 = r2/(r2 + 2000) x 9

Rearranging gives:
6r2 + 12000 = 9r2
so r2 = 4000 ohms

Doesn't ?
That's what the diagram says...

[physics]

what does a -ve voltage represent in a input voltage graph (sin) graph shape that goes up and down from +10 to -10V ? what does it mean
i'm confused but someone told me it means the current is reversed for a diode or somethin and i dont get how there can be a -ve voltage etc etc.

Not 100% sure, but I think it has to do with Alternating current (which you then convert to DC by the RMS forumula if you need to)

When Vout is 6 V what is the resisitance of the LDR?
i used the vout formula where the v out is 3 and i get 668933ohms which is wrong

Vout = (r2)/(r2 + r1) x Vin
So, 6 = r2/(r2 + 2000) x 9

Rearranging gives:
6r2 + 12000 = 9r2
so r2 = 4000 ohms

Can someone help me with what p and n type is? i have no idea.

From my basic understanding in trying to decode Heinmann 12, a semiconductor is "doped" (mixed with another element) to create a diode. Depending on the numer of electrons in the added element, the semiconductor will either lack an electron (p type - for overall positive charge) or have an extra electron (n type - overall negative charge).

why for the voltage do u use 6 and not 3 cause i was trying to find the diode and not the resistor? i did
3=9 *  (diode/ 2006800(total resistance)) = 668933ohms which is fail
sorry i'
m confused

[Chavi]

my bad - 2Mohms is 2,000,000 (million) ohms.

So the answer (if my calculations are correct) would be 4Mohm's for Vout

[physics]

3.4kohms lol...i am so confuseddd with how u get the answetrss T__T

[Chavi]

We know that
So in this case
Vout is 6 V
Vin = 9V
R2 = 2Mohm
R1 = unknown

[physics]

We know that
So in this case
Vout is 6 V
Vin = 9V
R2 = 2Mohm
R1 = unknown

i get it but the answer is ...wierd

[Blakhitman]

R2 is in the numerator.

and yeah the answer should be 4Mohms

[the.watchman]

R2 is in the numerator.

and yeah the answer should be 4Mohms

Yeah that's what I got (i did say that didn't i anna??? )

[physics]

R2 is in the numerator.

and yeah the answer should be 4Mohms

Yeah that's what I got (i did say that didn't i anna??? )

noooooooo u said 4Mohms which is 4000000 and not 4000 and hte answer is 3700ohms

[Blakhitman]

Are you sure R1 is 4 M ohms?, cause the only way you could get 4 k ohms, is if R1 is 2 K ohms.

but then again, why is the answer 3.7 k ohms? o.O

Which textbook? and what  chapter and question?