The level of liquid helium (temperature ≤ 4 K) in its storage lank can be monitored using a vertically aligned niobium–titanium (NbTi) wire, whose length ℓ spans the height of the tank. In this level-sensing setup, an electronic circuit maintains a constant electrical current I at all times in the NbTi wire and a voltmeter monitors the voltage difference V across this wire. Since the superconducting transition temperature for NbTi is 10 K, the portion of the wire immersed in the liquid helium is in the superconducting state, while the portion above the liquid (in helium vapor with temperature above 10 K) is in the normal state. Define f = x /ℓ to be the fraction of the tank filled with liquid helium (Fig. 25–40) and V 0 to be the value of V when the lank is empty ( f = 0). Determine the relation between f and V (in terms of V 0 ). FIGURE 25–40 Problem 95.
The level of liquid helium (temperature ≤ 4 K) in its storage lank can be monitored using a vertically aligned niobium–titanium (NbTi) wire, whose length ℓ spans the height of the tank. In this level-sensing setup, an electronic circuit maintains a constant electrical current I at all times in the NbTi wire and a voltmeter monitors the voltage difference V across this wire. Since the superconducting transition temperature for NbTi is 10 K, the portion of the wire immersed in the liquid helium is in the superconducting state, while the portion above the liquid (in helium vapor with temperature above 10 K) is in the normal state. Define f = x /ℓ to be the fraction of the tank filled with liquid helium (Fig. 25–40) and V 0 to be the value of V when the lank is empty ( f = 0). Determine the relation between f and V (in terms of V 0 ). FIGURE 25–40 Problem 95.
The level of liquid helium (temperature ≤ 4 K) in its storage lank can be monitored using a vertically aligned niobium–titanium (NbTi) wire, whose length ℓ spans the height of the tank. In this level-sensing setup, an electronic circuit maintains a constant electrical currentI at all times in the NbTi wire and a voltmeter monitors the voltage difference V across this wire. Since the superconducting transition temperature for NbTi is 10 K, the portion of the wire immersed in the liquid helium is in the superconducting state, while the portion above the liquid (in helium vapor with temperature above 10 K) is in the normal state. Define f = x/ℓ to be the fraction of the tank filled with liquid helium (Fig. 25–40) and V0 to be the value of V when the lank is empty (f = 0). Determine the relation between f and V (in terms of V0).
The level of liquid helium (temperature = 4 K) in its storage
tank can be monitored using a vertically aligned niobium-
titanium (NbTi) wire, whose length l spans the height of
the tank. In this level-sensing setup, an electronic circuit
Constant I
maintains a constant electrical current I at all times in the
Helium
NbTi wire and a voltmeter monitors the voltage differ-
ence V across this wire. Since the superconducting critical
temperature for NbTi is 10 K, the portion of the wire
immersed in the liquid helium is in the superconducting
state, while the portion above the liquid (in helium vapor
with temperature above 10 K) is in the normal state. Define
f = x/l to be the fraction of the tank filled with liquid
helium (Fig. 18–38) and Vo to be the value of V when the
tank is empty (f = 0). Determine the relation between
fand V (in terms of Vo).
vapor
(>10K)
Liquid
helium
(=4K)
FIGURE 18–38 Problem 91.
Superconducting
Normal
In a dorm, there are a few electric devices running at a voltage of 110 V. A refrigerator that runs with a current of 4.0 A, a heater with a resistor of 10 Ω at room temperature, a fan that exerts 12 Nm toque with a constant angular velocity of 8 rad/s. What is the total power? If the resistor in the heater has a temperature dependence with α = 0.01. When the heater reaches 500 ̊C, what is the change in total power in the dorm?
From Kirchoff's law, the current I in an RC (resistor-capacitor) circuit during discharging obeys the
equation
R ²+²=C² = (
di(t) 1(t)
dt
a. Find I (t).
b. For a capacitance of 10,000 uF charged to 100 V and discharging through a resistance of 1 m2, find the
current I for t = 0 and for t = 100 sec.
Note: The initial voltage is IR or Q/C, where I = dQ/dt.
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DC Series circuits explained - The basics working principle; Author: The Engineering Mindset;https://www.youtube.com/watch?v=VV6tZ3Aqfuc;License: Standard YouTube License, CC-BY