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When current is passed through a junction of two dissimilar metals, heat is evolved or absorbed at the junction. This process is called
In which of the following the power dissipation is proportional to the square of the current ?
Which of the following is not reversible?
Joule effect H = I2RT
When current flows heat is produced. But, by heating conduction current cannot produced.
Who among the following scientists made the statement ?“Chemical change can produce electricity”.
Galvani made the statement “Chemical change can produce electricity”.
Two electric bulbs whose resistance are in the ratio 1 : 2 are arranged in parallel to a constant voltage source. The powers dissipated in them have the ratio
The cold junction of a thermocouple is maintained at 10ºC.No thermo e.m.f. is developed when the hot junction is maintained at 530ºC. The neutral temperature is
Neutral temperature,
\(\theta _{n}=\frac{\theta _{i}+\theta _{0}}{2}=\frac{530+10}{2}\)=270º C.
A steady current of 5 A is maintained for 45 minutes. During this time it deposits 4.572 g of zinc at the cathode of voltameter.E.C.E. of zinc is
Electrochemical equivalent,
\(Z=\frac{m}{It}=\frac{4.572}{5\times 45\times 60}=3.387\times 10^{4}g/C.\)
A battery of e.m.f. 10 V and internal resistance 0.5 Ω is connected across a variable resistance R. The value of R for which the power delivered init is maximum is given by
According to maximum power theorem, the power in the circuit is maximum if the value of external resistance is equal to the internal resistance of battery.
In an electroplating experiment, m g of silver is deposited when 4A of current flows for 2 minutes. The amount in g of silver deposited by 6A of current for 40 seconds will be
Mass of substance deposited
m = ZI t = Z × 4(2 × 60) = 480 Z and
m' = Z × 6 × 40 = 240 Z or m' = m/2.
A dynamo develops 0.5 A at 6 V. The energy which is generated in one second is
Energy produced = V I t =6 × 0.5 × 1 =3.0 J.