Question

The temperature of a body shown by a faulty Celsius thermometer is 49 °C and by a correct Fahrenheit thermometer is 122 °F. The correction to be applied to the faulty thermometer is

• A. -12 °C
• B. +1 °C
• C. +12 °C
• D. -1 °C

Hint:

Distinguish between "error" and "correction". Error is how much the measurement is off (\(\text{True} - \text{Measured}\)). Correction is what you must add to the measurement to fix it (\(\text{Correction} = -\text{Error}\)). In this case, the error is -1°C (it reads 1°C too low), so the correction is +1°C.

Answer 1

The Correct Option is B

Step 1: Find the correct temperature in Celsius.
The correct Fahrenheit temperature is \(F = 122\) °F.
The formula to convert Fahrenheit to Celsius is \( C = \frac{5}{9}(F-32) \).
\( C_{correct} = \frac{5}{9}(122 - 32) = \frac{5}{9}(90) = 5 \times 10 = 50 \) °C.
So, the true temperature of the body is 50 °C.
Step 2: Compare the correct temperature with the reading from the faulty thermometer.
The faulty Celsius thermometer reads \( C_{faulty} = 49 \) °C.
The error in the reading is \( \text{Error} = \text{True Value} - \text{Measured Value} \).
Error = 50 °C - 49 °C = 1 °C.
Step 3: Determine the correction to be applied.
The correction is what needs to be *added* to the faulty reading to get the true reading.
Correction = True Value - Faulty Reading.
Correction = 50 °C - 49 °C = +1 °C.
A correction of +1 °C must be applied to the faulty thermometer's reading.