Circuit Lab B/C

Test your knowledge of various Science Olympiad events.
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Creationist127
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Re: Circuit Lab B/C

Post by Creationist127 » November 5th, 2020, 9:20 am

azboy1910 wrote:
November 4th, 2020, 9:21 am
Creationist127 wrote:
November 4th, 2020, 7:24 am
1. A capacitor has 1 cm^2 plates, .5 mm apart from each other (with nothing in between). What is its capacitance?
2. A resistor is a cylinder with 5 mm diameter and is 1 cm long, and has resistivity 1 Ω*m. What is its resistance?
3. The resistor and capacitor are placed in series with each other and a 9-volt battery. How long will it take for the capacitor to charge to 8.5 volts?
1. 1.77E(-10) F or 0.177 nF
2. 509.3 ohms
3. about 2.89 time constants
I worded q1 badly, I really meant "square, 1 cm to a side", but as "1 cm^2" your answer is right. 2 is right, and I was looking for an actual time (in seconds) for 3.
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Re: Circuit Lab B/C

Post by azboy1910 » November 5th, 2020, 9:31 am

Creationist127 wrote:
November 5th, 2020, 9:20 am
azboy1910 wrote:
November 4th, 2020, 9:21 am
Creationist127 wrote:
November 4th, 2020, 7:24 am
1. A capacitor has 1 cm^2 plates, .5 mm apart from each other (with nothing in between). What is its capacitance?
2. A resistor is a cylinder with 5 mm diameter and is 1 cm long, and has resistivity 1 Ω*m. What is its resistance?
3. The resistor and capacitor are placed in series with each other and a 9-volt battery. How long will it take for the capacitor to charge to 8.5 volts?
1. 1.77E(-10) F or 0.177 nF
2. 509.3 ohms
3. about 2.89 time constants
I worded q1 badly, I really meant "square, 1 cm to a side", but as "1 cm^2" your answer is right. 2 is right, and I was looking for an actual time (in seconds) for 3.
My bad, I misread that the same resistor and capacitor from questions 1 and 2 were used for question 3, I thought that they were separate. Sorry about that!

Edit: Anyway I believe the answer then would be
about 2.605E(-7) seconds
Last edited by azboy1910 on November 5th, 2020, 12:17 pm, edited 1 time in total.
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Re: Circuit Lab B/C

Post by Creationist127 » November 7th, 2020, 3:13 pm

azboy1910 wrote:
November 5th, 2020, 9:31 am
Creationist127 wrote:
November 5th, 2020, 9:20 am
azboy1910 wrote:
November 4th, 2020, 9:21 am

1. 1.77E(-10) F or 0.177 nF
2. 509.3 ohms
3. about 2.89 time constants
I worded q1 badly, I really meant "square, 1 cm to a side", but as "1 cm^2" your answer is right. 2 is right, and I was looking for an actual time (in seconds) for 3.
My bad, I misread that the same resistor and capacitor from questions 1 and 2 were used for question 3, I thought that they were separate. Sorry about that!

Edit: Anyway I believe the answer then would be
about 2.605E(-7) seconds
Looks good, your turn!
2018: Hovercraft, Thermo, Coaster, Solar System
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Re: Circuit Lab B/C

Post by azboy1910 » November 7th, 2020, 6:36 pm

1. Draw a Thevenin equivalent circuit for the circuit below using R5 as the load resistor.
Image
2. An electromagnet with a turn density of 1.5k turns/meter with a current of 50 mA passing through it has a nickel core (100 H/m). Calculate the magnetic field strength of the electromagnet.
3. Two wires are made of the same material and are of the same length. However, one of the wires (W1) has double the diameter than the other wire (W2). Assuming all other factors that would affect the resistance of these wires are the same for both wires, how many times greater is the resistance of W2 than W1?
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Re: Circuit Lab B/C

Post by UTF-8 U+6211 U+662F » November 8th, 2020, 6:55 pm

azboy1910 wrote:
November 7th, 2020, 6:36 pm
1. Draw a Thevenin equivalent circuit for the circuit below using R5 as the load resistor.
Image
2. An electromagnet with a turn density of 1.5k turns/meter with a current of 50 mA passing through it has a nickel core (100 H/m). Calculate the magnetic field strength of the electromagnet.
3. Two wires are made of the same material and are of the same length. However, one of the wires (W1) has double the diameter than the other wire (W2). Assuming all other factors that would affect the resistance of these wires are the same for both wires, how many times greater is the resistance of W2 than W1?
1. 0.5 V battery in series with the load and a 3.38 ohm resistor?
2. 7500 T?
3. W2 is 4x the resistance of W1.

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Re: Circuit Lab B/C

Post by azboy1910 » November 9th, 2020, 9:37 am

UTF-8 U+6211 U+662F wrote:
November 8th, 2020, 6:55 pm
azboy1910 wrote:
November 7th, 2020, 6:36 pm
1. Draw a Thevenin equivalent circuit for the circuit below using R5 as the load resistor.
Image
2. An electromagnet with a turn density of 1.5k turns/meter with a current of 50 mA passing through it has a nickel core (100 H/m). Calculate the magnetic field strength of the electromagnet.
3. Two wires are made of the same material and are of the same length. However, one of the wires (W1) has double the diameter than the other wire (W2). Assuming all other factors that would affect the resistance of these wires are the same for both wires, how many times greater is the resistance of W2 than W1?
1. 0.5 V battery in series with the load and a 3.38 ohm resistor?
2. 7500 T?
3. W2 is 4x the resistance of W1.
Ok, so here's what I got.

1. I got a 0.88 V battery in series with the load and a 3.06-ohm resistor.
2. I got 0.0094 T as an answer from the equation below:

(1500 turns/m)(50 mA/1000)(100 H/m)(4pi x 10^-7 H/m) = 0.0094 T 
3. Correct 

Let me know if you disagree. If not, your turn!
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Re: Circuit Lab B/C

Post by UTF-8 U+6211 U+662F » November 9th, 2020, 9:21 pm

azboy1910 wrote:
November 9th, 2020, 9:37 am
UTF-8 U+6211 U+662F wrote:
November 8th, 2020, 6:55 pm
azboy1910 wrote:
November 7th, 2020, 6:36 pm
1. Draw a Thevenin equivalent circuit for the circuit below using R5 as the load resistor.
Image
2. An electromagnet with a turn density of 1.5k turns/meter with a current of 50 mA passing through it has a nickel core (100 H/m). Calculate the magnetic field strength of the electromagnet.
3. Two wires are made of the same material and are of the same length. However, one of the wires (W1) has double the diameter than the other wire (W2). Assuming all other factors that would affect the resistance of these wires are the same for both wires, how many times greater is the resistance of W2 than W1?
1. 0.5 V battery in series with the load and a 3.38 ohm resistor?
2. 7500 T?
3. W2 is 4x the resistance of W1.
Ok, so here's what I got.

1. I got a 0.88 V battery in series with the load and a 3.06-ohm resistor.
2. I got 0.0094 T as an answer from the equation below:

(1500 turns/m)(50 mA/1000)(100 H/m)(4pi x 10^-7 H/m) = 0.0094 T 
3. Correct 

Let me know if you disagree. If not, your turn!
1. I broke the circuit at the battery instead of shorting it out. I am now getting 3.06 ohms. Also for the voltage, I forgot to remove R5, I am now getting the same answer as you.
2. The magnetic field is permeability times turns per length times current, so I believe it would be (1500 turns/m)(0.05 A)(100 H/m) = 7500 T. I believe your equation doesn't work out dimensionally because you multiplied by an extra H/m instead of replacing the permeability of free space with the permeability of nickel.
Next question: What is a relay and how does it work?

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Re: Circuit Lab B/C

Post by Krish2007 » November 17th, 2020, 8:46 am

UTF-8 U+6211 U+662F wrote:
November 9th, 2020, 9:21 pm
Next question: What is a relay and how does it work?
A relay is an electrically controlled switch, kind of like a transistor. It can work in multiple ways, but one way (the most common way?) is for it to use an electromagnet. The electromagnet controls the switch by moving a conductor into position to close the switch and allow current flow.  
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Re: Circuit Lab B/C

Post by UTF-8 U+6211 U+662F » November 17th, 2020, 1:13 pm

Krish2007 wrote:
November 17th, 2020, 8:46 am
UTF-8 U+6211 U+662F wrote:
November 9th, 2020, 9:21 pm
Next question: What is a relay and how does it work?
A relay is an electrically controlled switch, kind of like a transistor. It can work in multiple ways, but one way (the most common way?) is for it to use an electromagnet. The electromagnet controls the switch by moving a conductor into position to close the switch and allow current flow.  
Yep, your turn!

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Re: Circuit Lab B/C

Post by Krish2007 » November 17th, 2020, 2:16 pm

1) Which of the famous scientists in the rules found that electricity could be produced chemically?
2) List 4 properties of an ideal op-amp.
3) Image
Find V1 and V2.
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