If two electric bulbs have $40\,\,W$ and $60\,\,W$ rating at $220\,\,V$, then the ratio of their resistances will be

A wire when connected to $220\,\,V$ mains supply has power dissipation ${P_1}$. Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is ${P_2}$. Then ${P_2}:{P_1}$ is

In a copper voltmeter , if the current $(I)$ and time $(t)$ variations of the type as shown in figure, the mass deposited in ${\rm{30}}\,\,{\rm{min}}$ is [Atomic weight of copper is ${\rm{63}}{\rm{.5}}$ and Faraday constant is ${\rm{96500 C }}\,{\rm{per}}\,\,{\rm{g}}$ equivalent]

The heat produced by a ${\rm{100 W}}$ heater in $2\,\,min$ will be equal to

An AC generator of $220\,\,V$ having internal resistance $r = 10\,\,{\rm{\Omega }}$ and external resistance $R = 100\,\,{\rm{\Omega }}$. What is the power developed in the external circuit

A bulb has specification of one kilowatt and 250 volts, the resistance of bulb is

The rate of increase of thermo $e.{\rm{m}}{\rm{.f}}{\rm{.}}$ with temperature at the neutral temperature of a thermocouple

In a thermo-couple, one junction which is at 0\,^\circ C and the othe at $t{\mkern 1mu} {\mkern 1mu} ^\circ C$ the emf is given by $E = a{t^2} - b{t^2}$. The neutral temperature is given by

Two lamps rated at 3 kW and 6 kW are connected across a constant voltage supply. What is the ratio of the total power consumed when they are connected in series to the total power consumed when they are connected in parallel?

An electric bulb is marked ${\rm{100 }}\,{\rm{W, 230 }}\,{\rm{V}}$. If the supply voltage drops to ${\rm{115 }}\,{\rm{V}}$, what is the total energy produced by the bulb in ${\rm{10 }}\,\,{\rm{min}}$ ?

Thomson coefficient of a conductor is $10\,\,\mu V/K$. The two ends of it are kept at 50\,{\,^0}{\rm{C}} and 60\,{\,^0}{\rm{C}} respectively. Amount of heat absorbed by the conductor when a charge of $10\,\,C$ flows through it is