The resistance of the platinum wire of a platinum resistance thermometer at the ice point is 5 Ω and at steam point is 5.39 Ω. When the thermometer is inserted in a hot bath, the resistance of the platinum wire is 5.795 Ω. Calculate the temperature of the bath.

A battery has an emf of ε = 19 V, an internal resistance r = 28 22, and is connected to a resistor of R = 75 22. Express the current I through the circuit in terms of ε, r and R. Calculate the numerical value of I in A. Express the terminal voltage 4V of the battery in terms of I and R. Calculate the numerical value of 4V in V.

In one form of plethysmograph (a device for measuring volume), a rubber capillary tube with an inside diameter of 1.30 mm is filled with mercury at 20°C. The resistance of the mercury is measured with the aid of electrodes sealed into the ends of the tube. If 100.00 cm of the tube is wound in a spiral around a patient's upper arm, the blood flow during a heartbeat causes the arm to expand, stretching the tube to a length of 100.20 cm. From this observation, and assuming cylindrical symmetry, you can find the change in volume of the arm, which gives an indication of blood flow. Take ?Hg = 9.4 ✕ 10−7 Ω · m. (a) Calculate the resistance of the mercury. (b) Calculate the fractional change in resistance during the heartbeat. Hint: Because the cylindrical volume is constant, V = Ai Li = Af Lf and Af = Ai(Li/Lf).

Platinum is commonly used as a resistance thermometer since Platinum is relatively free from corrosive effects and has a high melting point. Suppose that at 20 oC the resistance of a Platinum wire is 164.2 Ω. When this wire is placed in a solution, the resistance of the wire becomes 187.4 Ω. What is the temperature of the solution? The temperature coefficient of resistivity of Platinum is α = 0.00393.