Home
Class 12
PHYSICS
The EMF generated across a thermocouple ...

The EMF generated across a thermocouple with cold junction at `0^(@)C` , is
`E=a theta+btheta^(2)`
with a `=30muV(.^(@)C)^(-1)` and `b=0.08muV(.^(@)C)^(-2)`
At E=6mV. The hot junction temperature is about

A

`14^(@)C`

B

`144^(@)C`

C

`323^(@)C`

D

`640^(@)C`

Text Solution

Verified by Experts

`E=atheta+btheta^(2)`
It is a quadratic equation
`btheta^(2)+a theta-E=0`
or `theta=(-a+-sqrt(a^(2)+4bE))/(2b)`
Now consider. `sqrt(a^(2)+4bE)` for solution
`sqrt(a^(2)+4bE)`
`=sqrt((30xx10^(-6))^(2)+4 xx0.08xx10^(-6)xx6xx10^(-3))`
`=5.3xx10^(-5)`
`therefore theta=(-3xx10^(-5)+5.3xx10^(-5))/(2xx0.08xx10^(-6))=144^ (@)C`
Promotional Banner

Similar Questions

Explore conceptually related problems

For a copper-iron and a chromel-alumel thermocouple, the plots between thermoelectric emf and the temperature theta of the hot junction (when the cold junction is at 0^(@)C )are found to satisfy approximately the parabola equation V=alpha theta+(1)/(2)betatheta^(2) with alpha=14muV^(@)C^(-1) beta=-0.04V^(@)C^(-2) (copper-iron) alpha=41muCV^(@)C^(-1),beta=-0.002V^(@)C^(-2) (chromel-alumel) Which of the two thermocouples would you use to measure temperature in the range of a about 500^(@)C to 600^(@)C ?

The emf varepsilon of a Cu-Fe thermocouple varies with the temperature theta of the hot junction (cold junction at 0^(@)C ), as varepsilon(mu V)=14 theta-0.02 theta^(2) Determine the neutral temperature.

The thermo emf of a therocouple , one junction of which is kept at 0^(@)C , is given by varepsilon=at+bt^(2) where a and b constants of the thermocouple . Calculate the neutral temperature and peltier and Thomson coefficients.

Thermo e.m.f. E of a Cu-Fe thermocouple varies with the temperature theta of the hot junction ( cold juction 0^(@)C ) as E(muV)=12theta-0.02 theta^(2) . Determine:- (a) Neutral temperature of the termocouple (b) Temperature of inversion, assuming that cold junction is at 20^(@)C . (c) Value of Seebeck coefficient at neutral temperature

The temperature of the cold junction of thermo-couple is 0^(@)C and the temperature of hot junction is T^(@)C . The e.m.f . is E=16T-0.04 T^(2)mu volts. The temperature of inversion is

With the cold junction at 0^(@)C the neutral temperature for a thermo-couple is obtained at 270^(@)C . The cold junction temperature is now lowered to -10^(@)C Obta in the (a) neutral temperature (b) the temperature of inversion in this case.

Three rods of the same dimensions have thermal conductivities 3 k , 2 k and k . They are arranged as shown, with their ends at 100^(@)C, 50^(@)C and 0^(@)C . The temperature of their junction is :-

Three identical rods have been joined at a junction to make it a Y shape structure. If two free ends are maintained at 60^(@)C and the third end is at 0^(@)C , then what is the junction temperature theta ? ltimg src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/ALN_PHY_R03_E09_001_Q01.png" width="80%"gt

The thermo emf E of a thermocouple is found to vary wit temperature T of the junction (cold junction is 0^(@)C ) as E=40T-(T^(2))/(20) The temperature of inversion for the thermocouple is

For a thermocouple, the neutral temperature is 300^(@)C and the temperature of its cold junction is 30^(@)C . If there is no deflection in the galvanometer, the temperature of the hot junction should be