As the temperature of hot junction increases, the thermo e.m.f.:
Always increases
Always decreases
May increase or decrease
Always remains constant
Which of the following is not reversible?
Joule effect
Peltier effect
Seebeck effect
Thomson effect
Antimony and bismuth are usually used in a thermocouple, because :
Negative thermal e.m.f. produced
Constant thermal e.m.f. produced
Lower thermal e.m.f. produced
Higher thermal e.m.f. produced
If the temperature of cold junction of thermocouple is lowered, then the neutral temperature :
Increases
Approaches inversion temperature
Decreases
Remains the same
Two ends of a conductor are at different temperatures the electromotive force generated between two ends is :
Seebeck electro motive force (e.m.f.)
Peltier electro motive force (e.m.f.)
Thomson electro motive force (e.m.f.)
None of the above
A current of 5 amperes is passing through a metallic wire of cross-section area 4 x 10-6 m2. If the density of the charge carrier in the wire is 5 x 1026/m3, the drift velocity of the electrons is
1/8 m/s
1/16 m/s
1/64 m/s
1/78 m/s
A tap supplies water at 200C. A man takes 11 liter water per minute at 370C from the geyser. The power of geyser is
525 W
1050 W
1575 W
2100 W
The plates of a parallel plate’s air capacitor are 2 cm apart. A slab of dielectric constant 5 and thickness 1 cm is placed between the plates with its faces parallel to them and the distance between the plates is altered so as to keep the capacitance of the new capacitor unchanged. The new separation between the plates is
2.2 cm
2.8 cm
3.0 cm
3.2 cm
Two positively charged particles each of mass 1.7 x 10-27 kg and carrying a charged of 1.6 x 10-19 are placed at a distance r apart. If each one experiences a repulsive force equal to its weight, then r is
1.17 m
1.71 m
0.117 m
0.171 m
Ratio of the electrostatic to gravitational force between two electrons placed at a certain distance in air will be (me=9.1 x 10-31 kg, e = 1.6 x 10-19 C and G =6.6 x 10-11 Nm2/kg2)
4.2 x1042
4.2 x 10-42
2.4 x 1024
2.4 x 10-24