At what temperature will the centigrade thermometer read one-fifth of the fahrenheit thermometer?

Updated April 24, 2017

By William Adkins

The Celsius (or centigrade) temperature scale is the most widely used around the world, although the Fahrenheit scale is more popular in the United States. The Celsius system was invented by Swedish astronomer Anders Celsius in 1742. It is based on the difference in temperature between the freezing and boiling points of water at standard atmospheric pressure. In 1954, the definition was changed slightly to base the Celsius scale on absolute zero. This change is important for scientific reasons but not in everyday life, so for most purposes, everyone uses the original definition. It’s not hard to read a Celsius thermometer once you understand the difference between the Fahrenheit and Celsius temperature scales.

Learn how the Celsius temperature scale is set up. The temperatures at which water freezes and boils under one standard atmosphere of air pressure are used to define the Celsius scale. The freezing point of water is labeled 0 (zero) degrees, and the boiling point is labeled 100 degrees. The temperature interval between is divided into exactly 100 equal parts or degrees.

Know the difference between the Fahrenheit and Celsius temperature scales. In the Fahrenheit system, 32 degrees is the freezing point of water, and 212 degrees is the boiling point. The Fahrenheit scale therefore divides the interval between the two into 180 degrees (212 minus 32 = 180). Each Celsius degree equals 1.80 Fahrenheit degrees. Another way to say this is that each Fahrenheit degree is 5/9 of a degree Celsius.

Learn how to convert from Celsius to the Fahrenheit scale to read a Celsius thermometer. To do this, multiply the Celsius degrees by 1.80 and add 32. For example, 10 degrees Celsius is converted to Fahrenheit by multiplying 10 degrees by 1.80 (equals 18) plus 32, giving you a Fahrenheit temperature of 50 degrees.

Know how to convert Fahrenheit degrees to Celsius degrees. First subtract 32 degrees, then multiply the result by 5/9 (0.556 on a calculator). For example, suppose a thermometer reads 68 degrees Fahrenheit. Subtract 32 from 68, leaving 36. Multiply 36 by 5/9, which equals 20 degrees Celsius.

Pay attention to the negative sign when you are dealing with temperature conversions. Sometimes a negative Celsius temperature can change to positive when you convert to the Fahrenheit scale. For instance, suppose you read a Celsius thermometer and it gives the temperature as -5 C. You convert to Fahrenheit the same way—multiply -5 degrees by 1.80 (equals -9), then add 32. Adding 32 to -9 equals 23 degrees Fahrenheit. But if you don’t pay attention to that minus sign and add 32 and 9, you’ll get 41, which is incorrect.

We will discuss here about the concept of temperature. We have already learned about various types of measurements like length, mass capacity and time. But if we have fever, non of these measurements can help us to find out how high a fever we have.

The temperature of an object is measured by an instrument is called thermometer. Now we will learn about the measurement of temperature.

Take two cups, one containing normal water and another containing hot water. Put your fore finger of one hand in one cup and of another hand in the other cup. We find, one contains cold water and the other contains hot water. But the question is how much cold and how much hot. To find this out, we need some measure of hotness or coldness.

Temperature is the degree of hotness or coldness of a body. The instrument which measures the temperature of body is known as thermometer.

Each thermometer has a scale. Two different temperature scales are in common use today:

1. The Fahrenheit Scale

2. The Celsius Scale

Celsius and Fahrenheit thermometers

Thermometer has scale in degree Fahrenheit (℉) and in degree Celsius (℃). The Fahrenheit scale has the melting point of ice at 32° F and the boiling point of water at 212° F. Thus, the Fahrenheit scale is marked from 32° to 212° where 32° F shows the freezing point of water and 212° F shows the boiling point of water. At present most of the countries use the degrees Celsius thermometers. The Celsius scale (is also called centigrade scale) thermometer has 0° C as freezing point of water and 100° C as the boiling point of water.

On comparing the Celsius and Fahrenheit scale we find:

For Example:

Write True or False.

1. The instrument used to measure body temperature in thermometer -----

True.

2. The normal body temperature is 98.6°F ----- True.

3. The liquid inside the thermometer is mercury ----- True.

4. The unit of measure of temperature is inches ----- False.

5. 0°C is cooler than 0°F----- False.

● Temperature.

Converting the Temperature from Celsius to Fahrenheit.

Converting the Temperature from Fahrenheit to Celsius.

Clinical Thermometer.

Worksheet on Temperature.

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QUESTION #51

Asked by: Hamid A. Khan The temperature at which Fahrenheit and Celsius thermometer readings are equal is: - 40 degrees. Well if you look at the conversion formulas for Celsius to Fahrenheit, or that of Fahrenheit to Celsius, you can manipulate it mathematically to answer this question. The conversion formula reads:

T(F) = T(C) x 9/5 + 32

this means that the temperature of Fahrenheit equals the temperature of Celsius multiplied by nine / fifths, plus 32 degrees. If the temperatures are the same then the two 'T's' in the formula should represent the same temperature. So,

t = t x 9/5 + 32

minus the nine fifths of t from each side to move it to the left of the equation. this leaves: t - 9t/5 = 32 ------> this leaves: - 4t/5 = 32

so then you multiply each side by - 5/4 to solve for t, and you get t = - 40 degrees!

(by the way, 't' times,(x), nine/fifths equals 9t/5)

Answered by: Dominic Jones, D.B., High School Student

Answer

Verified

Hint: The relation between the Fahrenheit and centigrade is linear in nature. We will use the relation between the two scales and place the value of temperature given in the question

Formula used: In this solution, we will use the following formula:

$ C = \dfrac{5}{9}(F - 32) $ where $ C $ is the temperature in the centigrade scale and $ F $ is the temperature in Fahrenheit scale.

Complete step by step answer

The relation between the temperature of an object in centigrade and Fahrenheit is given as: $ C = \dfrac{5}{9}(F - 32) $ We want to find the point where the reading on the Fahrenheit scale is five times that on the Celsius scale. This implies that we can write $ F = 5C $ . Substituting this value in the above equation, we get $ C = \dfrac{5}{9}(5C - 32) $ Multiplying both sides by $ 9 $ , we get $ 9C = 5(5C - 32) $ Solving for $ C $ , we get $ 25C - 9C = 160 $ Simplifying the above term, we get $ 16C = 160 $ Which give us $ C = 10^\circ $ .

Additional information

In the Fahrenheit scale, the reference temperatures are $ 32\;^\circ F $ as a freezing point of water and $ 212\;^\circ F $ as a boiling point of water. Whereas in the Celsius scale $ 0\;^\circ C $ is the freezing point of water and $ 100\;^\circ C $ is the boiling point of water. Both scales are related directly and linearly which means that if the temperature of an object rises, its value rises both in the centigrade and in the Fahrenheit scale. The common point of both scales is $ - 40^\circ C $ which means that both the centigrade and the Fahrenheit scales will have the same value i.e. $ - 40^\circ C = - 40^\circ F $ .

Note

We must know the conversion of different temperature scales to answer such questions. Celsius and Fahrenheit are the most widely used temperature scales worldwide along with the Kelvin scale so we must at least know their interconversions.