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A platinum resistance thermometer wire has a resistance of 70hms at 0°Cand 7.5 Ohm...


Question

A platinum resistance thermometer wire has a resistance of 70hms at 0°Cand 7.5 Ohms at 100°C. Calculate the temperature of the wire when the resistance is 7.2 Ohms

Options

A)
15°C
B)
40°C
C)
20°C
D)
10°C

The correct answer is B.

Explanation:

R0 = 7Ω , R1 = 7.2 Ω, R2 = 7.5 Ω, Tx = ?

[(X – T100°C) ÷ (R1 - R0)] = [(T100°C – T0°C) ÷ (R2 - R0)]

[(Tx – 0) ÷ (72 – 7)] = [(100 – 0) ÷ (7.5 – 7)]

Tx/0.2 = (100 ÷ 0.5)

Tx = [(0.2 × 100)] ÷ 0.5

= 20/0.5 = 40°C


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Dicussion (1)

  • R0 = 7Ω , R1 = 7.2 Ω, R2 = 7.5 Ω, Tx = ?

    [(X – T100°C) ÷ (R1 - R0)] = [(T100°C – T0°C) ÷ (R2 - R0)]

    [(Tx – 0) ÷ (72 – 7)] = [(100 – 0) ÷ (7.5 – 7)]

    Tx/0.2 = (100 ÷ 0.5)

    Tx = [(0.2 × 100)] ÷ 0.5

    = 20/0.5 = 40°C

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