Two bulbs consume the same power when operated at $200\, V$ and $300\, V$ respectively. When these bulbs are connected in series across a $D.C.$ source of $500\, V$,then:

$A$ room has an $AC$ running for $5$ hours a day at a voltage of $220$ $V$. The wiring of the room consists of $Cu$ wire of $1$ $mm$ radius and a length of $10$ $m$. Power consumption per day is $10$ commercial units. What fraction of it goes into Joule heating in the wires? What would happen if the wiring is made of aluminium of the same dimensions? $(\rho_{Cu} = 1.7 \times 10^{-8} \, \Omega m, \rho_{Al} = 2.7 \times 10^{-8} \, \Omega m)$

There are two electric bulbs of $40\, W$ and $100\, W$. Which one will be brighter when first connected in series and then in parallel?

The $emf$ of a thermocouple, with one junction kept at $0^{\circ}C$, is given by the equation $e = at + bt^2$. The Peltier coefficient is given by:

The current flowing through a copper voltameter is $1.5\ A$. If the surface area of the electrode plate is $50\ cm^2$,the thickness of the copper layer deposited on this surface in $20\ min$ will be: (Density of copper = $9000\ kg/m^3$ and Electrochemical equivalent of copper = $0.00033\ g/C$)

For a thermocouple,the neutral temperature is $270\,^\circ C$ and the temperature of its cold junction is $20\,^\circ C$. If there is no deflection in the galvanometer,the temperature of the hot junction should be .............. $^\circ C$