If 43.0 m of nichrome wire is to have a resistance of 10.0 ohm at 20 degree , wh
ID: 1388942 • Letter: I
Question
If 43.0 m of nichrome wire is to have a resistance of 10.0 ohm at 20 degree , what diameter wire should be used? The resistance of a conductor is 19.4 ohm at 1.50 degree and 21.0 ohm at 95.0 degree. What is the temperature coefficient of resistance of the material? Round your final answer to five significant figures. If a 86.7 V emf is connected to the terminals A and B and the current in the 4 ohm resistor is 10 A. what is the value of the unknown resistor R ? What is the equivalent capacitance between points A and B if C = 1.0 mu F?Explanation / Answer
1)
rho = resistivity of nichrome = 100e-8 ohm m
resistane R= rho*L/A
10 = 100e-8*43/A
A = 100e-8*43/10
A = 4.3e-6 m^2
A = area of cross setion A = pi*d^2/4
d = diameter of the wire
3.14*d^2/4 = 4.3e-6
d = 2.34 mm <--------answer
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alfa = (R2-R1)/(R1*dT)
alfa= (21-19.4)/(19.4*(95-1.5))
alfa = 8.82*10-4 0C^-1
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current in 4 ohm resistor = total current = I
I = Vab/Req
Req = Vab/i = 86.7/10 = 8.67 ohms
R & 3 ohms are in series R1 = R + 3
R1 & 8 are in parallel
R2 = (R1*8)/(R1+8) = ((R+3)*8)/(R+11)
R2 & 4 ohms are in series Req = R3 + 4 = ((R+3)*8)/(R+11) + 4
Req = 8.67
((R+3)*8)/(R+11) + 4 = 8.67
((R+3)*8)/(R+11) = 4.67
8R + 24 = 4.67R + 51.37
3.33R = 27.37
R = 8.22 ohms <-----answer
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8 uF & C are in series
C1 = (8*1)/(8+1) = 8/9 uF
C1 & 1.4 are i parallel
C2 = C1 + 1.4 = (8/9) + 1.4 uF = 2.3 uF
C2 & 2.4 are in series
Ceq = C2*2.4/(C2+2.4) = 1.17 uF <-----answer