Circuit Lab B/C

Cathy-TJ
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Re: Circuit Lab B/C

Post by Cathy-TJ » March 13th, 2019, 3:37 pm

mjcox2000 wrote:Since no one has posted a question yet:

An LED with voltage drop and internal resistance is in series with a voltage and resistance . The LED’s maximum rated current is , and the minimum current at which its light is visible is .

1. What is the minimum series voltage for the LED to emit visible light?
2. Given the value of , write equations for the minimum and maximum value of for the LED to emit visible light without burning out.
Voltage = [math]10^-^4 (R+2)+3.2[/math]  Volts

Min R = [math][(V-3.2)/10^-^2]-2[/math] Ohms
Max R = [math][(V-3.2)/10^-^4]-2[/math] Ohms
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Re: Circuit Lab B/C

Post by mjcox2000 » March 13th, 2019, 4:58 pm

Cathy-TJ wrote:
mjcox2000 wrote:Since no one has posted a question yet:

An LED with voltage drop and internal resistance is in series with a voltage and resistance . The LED’s maximum rated current is , and the minimum current at which its light is visible is .

1. What is the minimum series voltage for the LED to emit visible light?
2. Given the value of , write equations for the minimum and maximum value of for the LED to emit visible light without burning out.
Voltage = [math]10^-^4 (R+2)+3.2[/math]  Volts

Min R = [math][(V-3.2)/10^-^2]-2[/math] Ohms
Max R = [math][(V-3.2)/10^-^4]-2[/math] Ohms
Looks good. Your turn!
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Re: Circuit Lab B/C

Post by Cathy-TJ » March 14th, 2019, 6:17 pm

What are the values of R3 and R4 if you want the battery to supply 83.3 mA to the circuit while the ammeter reads 0.00mA?

Image:https://drive.google.com/open?id=1_cVQz ... GLcoC9kaRg
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Re: Circuit Lab B/C

Post by mjcox2000 » March 14th, 2019, 6:45 pm

Cathy-TJ wrote:What are the values of R3 and R4 if you want the battery to supply 83.3 mA to the circuit while the ammeter reads 0.00mA?

Image:https://drive.google.com/open?id=1_cVQz ... GLcoC9kaRg
The 0 current condition requires that [math]\frac{R_3}{R_4}=\frac{20}{280}[/math], and the 83.3mA current condition requires that the total parallel resistance be [math]180\Omega[/math], so [math]R_3+R_4=450\Omega[/math], so [math]\boxed{R_3=30\Omega,\ R_4=420\Omega}[/math].
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Re: Circuit Lab B/C

Post by Cathy-TJ » March 14th, 2019, 6:54 pm

mjcox2000 wrote:
Cathy-TJ wrote:What are the values of R3 and R4 if you want the battery to supply 83.3 mA to the circuit while the ammeter reads 0.00mA?

Image:https://drive.google.com/open?id=1_cVQz ... GLcoC9kaRg
The 0 current condition requires that [math]\frac{R_3}{R_4}=\frac{20}{280}[/math], and the 83.3mA current condition requires that the total parallel resistance be [math]180\Omega[/math], so [math]R_3+R_4=450\Omega[/math], so [math]\boxed{R_3=30\Omega,\ R_4=420\Omega}[/math].
You're correct!
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Re: Circuit Lab B/C

Post by UTF-8 U+6211 U+662F » April 15th, 2019, 2:41 pm

Restarting... what force is exerted between two protons one meter apart?

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Re: Circuit Lab B/C

Post by krasabnk » April 15th, 2019, 4:40 pm

UTF-8 U+6211 U+662F wrote:Restarting... what force is exerted between two protons one meter apart?
Using Coulomb's law and knowing protons are elementary charges.... F = (9x10^9)(1.6x10^-19)(1.6x10^-19) / (1)^2... Would the answer be 2.30x10-28 N?
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Re: Circuit Lab B/C

Post by UTF-8 U+6211 U+662F » April 15th, 2019, 5:18 pm

krasabnk wrote:
UTF-8 U+6211 U+662F wrote:Restarting... what force is exerted between two protons one meter apart?
Using Coulomb's law and knowing protons are elementary charges.... F = (9x10^9)(1.6x10^-19)(1.6x10^-19) / (1)^2... Would the answer be 2.30x10-28 N?
Seems right, your turn!

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Re: Circuit Lab B/C

Post by krasabnk » April 15th, 2019, 6:06 pm

C Only
Image
Given this orientation of an operational amplifier, find the value of Rf (in kΩ) if the Vin = 20 mV, Rg = 3.8 kΩ, and Vout = 64 mV
(sorry for my bad drawing, haha)
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Re: Circuit Lab B/C

Post by UTF-8 U+6211 U+662F » April 15th, 2019, 6:24 pm

krasabnk wrote:Image
Given this orientation of an operational amplifier, find the value of Rf in kΩ if the Vin = 20 mV, Rg = 3.8 kΩ, and Vout = 64 mV
(sorry for my bad drawing, haha)
I love this drawing
8.36 kiloohms?

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