A thermoelectric refrigerator works on :
Joule effect
Seeback effect
Peltier effect
Thermonic emission
If the temperature of cold junction of thermocouple is lowered, then the neutral temperature :
Increases
Approaches inversion temperature
Decreases
Remains the same
If a resistance 5 is connected in the left gap of a meter bridge and 15 in the other gap then position of balancing point is
10 cm
20 cm
25 cm
75 cm
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
If two electrons are separated by a distance of 0.5A, then ratio of coulomb force and weight of electron is approximately
1016
1018
1020
1022
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
An air filled parallel-plate capacitor has a capacitance of 10-12 fared. Separation of the plates is doubled and wax inserted between them, which makes the capacitance 2 x 10-12 fared. This implies that the dielectric constant of the wax is
2.0
3.13
4.0
8.00
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
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
In the Bohr’s model of hydrogen atom, the electron moves around the nucleus in a circular orbit of radius 5x 10-11 metres. If its time period is 1.2 x 10-16 sec, then current associated with the electron motion is
Zero
1.6 x 10-19 A
0.17 A
1.07 X 10-3 A