1. Design a solenoid that will produce a magnetic field of 0.047 T using a curre
ID: 1284822 • Letter: 1
Question
1. Design a solenoid that will produce a magnetic field of 0.047 T using a current I = 24 A. If the radius of the solenoid is 5 cm and the solenoid is 4.1 m long, how many turns of wire are required?
2. Use the exact values you enter in previous answer(s) to make later calculations.
The battery in the figure below is a real battery. That is, it has some internal resistance Rint in series with an ideal battery with an emf of V0. In an attempt to determine Rintand V0, a resistor
R1 = 700 ?
is first placed across points A and B, and the voltage across the resistor is measured to be 5.0 V. This resistor is then replaced with a second resistor with
R2 = 2,400 ?,
and the voltage across R2 is found to be 9.8 V. Find Rint and V0.
(a) Express the resistors in parallel as a single equivalent resistor. What is the value of this resistor?
?
(b) Combine this equivalent resistor with R1 to get the total equivalent resistance of the circuit. What is the value of this resistor?
?
(c) The circuit is now "reduced" to a battery in series with a single equivalent resistance. Use your result from part (b) to find the current through the battery and resistor R1.
A
4.
Consider the circuit in the figure below with resistors R1 = 540 ?, R2 = 430 ?, R3 = 280 ?, and R4 = 186 ?.
What is the equivalent resistance between points A and B?
?
Explanation / Answer
1.
Magnetic field due to a solenoid is
B=uoN*I/L
=>N=B*L/uo*I =0.047*4.1/(4pi*10-7)*24
N=6390 turns
2.
at V=5 volts and R1=700 ohms
I=V/R =5/700=7.143*10-3 A
Emf
Vo=V+IRint
Vo=5+(7.143*10-3)Rint
Vo-(7.143*10-3)Rint=5-------------------1
at V=9.8 V and R=2400 ohms
I=V/R =9.8/2400 =4.083*10-3 A
Emf
Vo=9.8+(4.083*10-3)Rint
Vo-(4.083*10-3)Rint=9.8---------------2
solving 1 and 2 we get
Vo=16.2 Volts
Rint=1568.63 ohms
3)
a)
1/R23=1/R2+1/R3 =1/1800 +1/4400
R23=1277.42 ohms
b)
equivalent resistance
Req=R1+R23=2700+1277.42
Req=3977.42 ohms
c)
I=E/Req=1.6/3977.42
I=4.02*10-4 A or 0.402 mA
4)
R2 and R4 are in series
R24=430+186=616 ohms
R3 and R24 are in parallel
1/R234=1/616+1/280
R234=192.5 ohms
R1 and R234 are in series ,so equivalent resistance
Req=540+192.5=732.5 ohms
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