Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A thermocouple of resistance 1.6Ω is connected in series with a galvanometer of 8Ω resistance. The thermocouple develops and e.m.f. of 10 μV per degree temperature difference between two junctions. When one junction is kept at 0℃  and the other in a molten metal, the galvanometer reads 8 millivolt. The temperature of molten metal, when e.m.f. varies linearly with temperature difference, will be

(a) 960℃

(b) 1050℃

(c) 1275℃

(d) 1545℃

The resistance of a wire is   per metre. It is bend in the form of a circle of diameter 2 m. A wire of the same material is connected across its diameter. The total resistance across its diameter AB will be

(a)

(b)

(c) 0.88

(d) 14π

Emission spectrum of CO₂​ gas:

A long, straight wire carries a current along the z-axis, One can find two points in the x−yplane such that:

Out of dia, para and ferromagnetism, the universal property of all substances is:

In case of a Van de Graaff generator, the breakdown field of air is:

A coil has an inductance of 2.5 H and a resistance of 0.5 r. If the coil is suddenly connected across a 6.0 volt battery, then the time required for the current to rise 0.63 of its final value is

(a) 3.5 sec

(b) 4.0 sec

(c) 4.5 sec

(d) 5.0 sec

The peak voltage in a 220V AC source is:

The magnifying power of a simple microscope can be increased, if we use eye-piece of

(a) Higher focal length	(b) Smaller focal length
(c) Higher diameter	(d) Smaller diameter