Current and Voltage of Elements of a Circuit with a Solenoid.

Join the discussion
Registration is free. Start your own thread to ask a follow-up.
4 replies · 3K views
Thadis
Messages
43
Reaction score
0
Ended up figuring out how to solve this problem. I just was not expecting certain parts of the results which lead me to believe I did it wrong.

Homework Statement



2R_switch_2.jpg


Voltage of battery is 5V
Resistors are 5 Ohms
The solenoid has no internal resistance

1.Need to find V_2 before switch is opened
2.The current through the solenoid right after the switch has been opened.
3. The current through R_2 and R_1 right after the switch has been opened.
4. Voltage across R_1 right after the switch has been opened.
5. Voltage across R_1 if it was 5 Mohms right after the switch has been opened.

Homework Equations


V=IR
Kirchhoff's Loop Rule

That a solenoid will want to resist any change in current.

The Attempt at a Solution


1. The voltage across R_2 will be 5V because the loop that consists of the switch and resistor has to have a voltage drop of 5 V and the resistor is the only element with a voltage drop on that loop.

2. The current through the solenoid right after the switch is open will be 1 A as the solenoid will want to keep the same current as before.

3. 1 A as the current will be same as the solenoid.

4. The voltage drop across both of the resistors will be 5 V. The solenoid will add additional voltage to create the greater voltage.

5. 5*10^6 V as the current will still be 1 A.I know I probably have flawed logic in here somewhere though I just do not know exactly how a solenoid will effect this circuit after the switch is thrown.
 
Last edited:
Physics news on Phys.org
Just after the switch has been opened. Sorry thought I put that in the questions but I must of missed putting that there.
 
Thadis said:
Just after the switch has been opened. Sorry thought I put that in the questions but I must of missed putting that there.

Everything is correct. Congrats!
 
Yeah I ended up getting the answers back and I got a happy surprise when I saw that I was correct. I guess that's why they put the question in the post lab, to show how solenoids can do this.