Numerical - temperature of platinum resistance thermometer given R- Thermodynamics
        
	  
	
    Q.  A platinum resistance thermometer has a resistance of 2 ohm at 0° C and 3 ohm at 100° C. What will be the temperature when resistance indicates 5 ohm?- Published on 21 Aug 15a. 300° C
b. 200° C
c. 350° C
d. 400° C
ANSWER: 300° C
 
The resistance and temperature relation is given by R = R0 (1 + αt) by electric resistance thermometer.
where R0   is the resistance at  0° C
R0  = 2 ohm
R100  =3 ohm
 = (1 + α 100)
Therefore α = 0.005
Now, 
R= 5 ohm
5 = 2 (1 + 0.005t)
t = 300° C