Question

The temperature of a body is measured using the resistance of a wire. To calibrate the device the following measurements were taken (ohms is the unit of electrical resistance).

Resistance in melting ice 240 ohms.

Resistance in boiling water 250 ohms.

a. What is the change in resistance for a change in temperature of 1 Degree Celcius?

b. The wire is placed into some hot water and the resistance is mesured to be 246 ohms. What is the temperature of the water?

Answer 1

The change in resistance per degree Celsius is 0.1 ohms. Using this value, we can determine that the temperature of the water, which has a resistance of 246 ohms, is 60°C.

Step-by-step explanation:

To determine the change in resistance per degree Celsius, we first calculate the total change in resistance between the melting point of ice and boiling point of water. This is given by the difference between the two resistances:

Change in resistance = Resistance at boiling point - Resistance at melting point = 250 ohms - 240 ohms = 10 ohms.

Since the temperature difference between melting ice and boiling water is 100 degrees Celsius (0°C to 100°C), we can find the change in resistance per degree as follows:

1. Change in resistance per 1°C = Total change in resistance / Temperature change = 10 ohms / 100°C = 0.1 ohms/°C.

Now, let's calculate the temperature of the water when the resistance is 246 ohms:

1. Difference in resistance = Measured resistance - Resistance at melting point = 246 ohms - 240 ohms = 6 ohms.
2. Temperature change = Difference in resistance / Change in resistance per 1°C = 6 ohms / 0.1 ohms/°C = 60°C.
3. Temperature of the water = Temperature at melting point + Temperature change = 0°C + 60°C = 60°C.

The temperature of the hot water is therefore 60°C when the resistance is 246 ohms.

Answer 2

A)250-240

=10+960

=970