Explanation
When current is passed through a junction of two different metals heat is either evolved or observed. This effect is known as Peltier effect.
Thermoelectric series is arrangement of metals in a certain sequence. The direction of current at hot junction is from metal occuring earlier in series to one occuring earlier in series to one occuring later in series same of the substances in series are Bi, Ni, Co, Pd, Pt, Cu, Mn,…….etc. The more separated metals are in the series, the greater is the value of thermo emf generated. Thus emf drveloped in Sb – Bi thermocouple is higher than other thermocouples.
When a circuit is made up of any two metals in thermoelectric series, the current flows across the cold junction from the later occuring metal in the series to the one occuring earlier. In thermoelectric series bismuth comes earlier than antimany. So at cold junction current flows from antimony to bismuth and vice versa.
When K is opened, brightness of bulb B1 decreases because bulb B2 will not draw any current from source. So, power consumed by bulb increases so light of bulb becomes more.
Peltier coefficient :- The amount of heat absorbed or evolved at junction of two different metals when one coulomb of charge flows at the junction.
Thomson effect :- Heat is absorbed or evolved in excess of joule heat when a current is passed through an unequally heated conductor.
So, B is false.
Fuse wire is made of tin-lead alloy (63% tin + 37%) lead).
A bulb will glow with maximum brilliancy, for which current is maximum and the maximum current flows in bulbs 1 and 5
When key is closed, the effective resistance of the circuit decreases and hence current in bulb A increases. Due to it A glows with more intensity. But as B is shunted, its glow decreases.
Heat produced H = VI t/4.2 calories.
Heat produced, H = P × t to decrease t, for the given H, P should increase. But P ∝ 1/R, therefore R should decrease. Since R ∝ 1, hence l should decrease
The resistance of 15 bulbs in series is less than that of 20 bulbs in series. Since illumination produced is proportional to heat produced (=V2 t/R) hence I2 > I1.
E.M.F. of the alkali cell is 1.35 V and that of acid cell is 2.2V.
m = z I t or m ∝ I.
The ratio of the weights deposited on cathodes will be in the ratio of their chemical equivalents. The chemical equivalent of copper = At wt/2 and that of silver = At wt/1.
During charging of lead-acid accumulator, the sp.gr. of H2SO4 increases.
Please disable the adBlock and continue. Thank you.