On an electric heater $220\, volt$ and $1100\, watt$ are marked. On using it for $4$ hours, the energy consumed in $kWh$ will be

A uniform heating wire of resistance $36\, \Omega$ is connected across a potential difference of $240\, {V}$ The wire is then cut into half and potential difference of $240\, {V}$ is applied across each half separately. The ratio of power dissipation in first case to the total power dissipation in the second case would be $1: {x}$, where ${x}$ is........... .

If in the circuit, power dissipation is $150\, W$, then $R$ is ............... $\Omega$

$(a)$ Consider circuit in figure. How much energy is absorbed by electrons from the initial state of no current (ignore thermal motion) to the state of drift velocity ?

$(b)$ Electrons give up energy at the rate of $R{I^2}\;$ per second to the thermal energy. What time scale would number associate with energy in problem $(a)$ ? $n = no$ of electron/volume $ = {10^{29}}{m^{ - 3}}$, length of circuit $= 10$ $cm$, cross-section $=$ $A = $ ${\left( {1\,mm} \right)^2}$

A uniform metallic wire of length $L$ is mounted in two configurations. In configuration $1$ (triangle), it is an equilateral triangle and a voltage $V$ is applied to corners $A$ and $B$. In configuration $2$ (circle), it is bent in the form of a circle and the potential $V$ is applied at diametrically opposite points $P$ and $Q$. The ratio of the power dissipated in configuration $1$ to configuration $2$ is

An electric kettle has two heating coils. When one of the coils is connected to an a.c. sotuce, the water in the kettle boils in $10$ minutes. When the other coil is used the w’ater boils in $40$ minutes. If both the coils are connected in parallel, the time taken by the same quantity of water to boil will be ...... $min$