The internal resistance of a primary cell is $4\, ohm$. It generates a current of $0.2\, amp$ in an external resistance of $21\, ohm$. The rate at which chemical energy is consumed in providing the current is .............. $J/s$

A resistance $R = 12\, \Omega$ is connected across a source of emf as shown in the figure . Its $emf$ changes with time as shown in the graph . What is the heat developed in the resistance in the first four seconds ? ............. $J$

A $60\, watt$ bulb operates on $220\,V$ supply. The current flowing through the bulb is

A $50 \,W$ bulb connected in series with a heater coil is put to an $AC$ mains. Now the bulb is replaced by a $100 \,W$ bulb. The heater output will ...........

One $kg$ of water, at $20\,^oC$, is heated in an electric kettle whose heating element has a mean (temperature averaged) resistance of $20\, \Omega $. The rms voltage in the mains is $200\, V$. Ignoring heat loss from the kettle, time taken for water to evaporate fully, is close to.......... $\min$ [Specific heat of water $= 4200\, J/kg\, ^oC$), Latent heat of water $= 2260\, k\,J/kg$]

Figure shows three resistor configurations $\mathrm{R} 1, \mathrm{R} 2$ and $\mathrm{R} 3$ connected to $3 \mathrm{~V}$ battery. If the power dissipated by the configuration $\mathrm{R} 1, \mathrm{R} 2$ and $\mathrm{R} 3$ is $\mathrm{P} 1, \mathrm{P} 2$ and $\mathrm{P} 3$, respectively, then

Figure: