I've attached the circuit problem as a picture.

I worked out the ideal voltage to be 50 V.

The resistance should be 8 ohms.

Having trouble finding the current when the voltage is 22 V.

Is Ohm's law sufficient to find this current?



Moderators note : shown image full size

 

Hello,

You are right about the voltage of 50 Volts and the resistor being 8 Ohms.
When the Vi = 22 volts, the current will be coming out of the device.
The value will be negative.
Can you calculate the current now?

Bertus

 

I honestly don't know. I know I am close; but, I've never seen questions like this in the past and I'm lacking intuition for these questions that I know will end up being easy to me (not easy at the moment).

 

Hello,

How did you calculate the voltage source and resistance?

Bertus

 

The current I want is -28 / 8? This is 'cause...

(50 - 22) / (0 - i) = 8

28 / -i = 8

28 = -8i

i = -28 / 8.

 

Hello,

So the current would be -28/8 = -3.5 Amps, wich is correct.

Bertus

 

Table looks linear (plot it on graph paper), so


I = aX + b equation of straight line

first table entry

0 = a x 50 + b or b = -( a x 50 )

second table entry

2 = a x 66 + b = a x 66 - a x 50 = 16 x a or a = 1/8

Therefore b = -(a x 50) = - 50 / 8 = -6.25

Therefore

I = V/8 - 6.25 general equation

For 22 V

I = 22/8 - 6.25 = 2.75 - 6.25 = - 3.5

Check last entry

10 = 130/8 - 6.25 = 10


Regards, Dana.

 

Cheers, people.

 

Hello,

You are right about the voltage of 50 Volts and the resistor being 8 Ohms.
When the Vi = 22 volts, the current will be coming out of the device.
The value will be negative.
Can you calculate the current now?

Bertus

I'd say it's a 50 Volt Zener with a 8 Ohm resistor. so the current would be 0 at Vi = 22 volts.

 

Hello,

@Ramussons , That is also an other possibility, but in the question there is an ideal voltage source is asked for.

Bertus.

PS I have shown the image full size in the openings post

 

Hello,

@Ramussons , That is also an other possibility, but in the question there is an ideal voltage source is asked for.

Bertus.

PS I have shown the image full size in the openings post

Oops, I missed that point