Draw a schematic diagram of a circuit consisting of a cell of $1.5 \,V , 10 \Omega$ resistor and $15 \,\Omega$ resistor and $a$ plug key all connected in series.

Three bulbs of $40\, W , 60\, W$ and $100\, W$ are connected in series across the mains. Across which the potential difference is highest? Across which is lowest ?

A current of $1$ ampere flows in a series circuit containing an electric lamp and a conductor of $5\,\Omega $ when connected to a $10\, V$ battery. Calculate the resistance of the electric lamp.

Now if a resistance of $10\,\Omega $ is connected in parallel with this series combination, what change (if any) in current flowing through $5\,\Omega $ conductor and potential difference across the lamp will take place? Give reason.

Draw a schematic diagram of an electric circuit consisting of a battery of two cells each of $1.5\, V$, $5\, \Omega, 10\, \Omega$ and $15\, \Omega$ resistors and a plug key, all connected in series.

When a high resistance voltmeter is connected directly across an electric bulb, its reading is $2\, V$ An electric cell is sending the current of $0.4$ ampere (measured by. an ammeter) in the electric circuit.

$(a)$ Draw the circuit.

$(b)$ Find the resistance of the electric bulb.

$(c)$ State the law that is applied for making these calculation. If a graph is plotted between $V$ and $I,$ show the nature of the graph obtained.

Calculate the number of electrons constituting one coulomb of charge.

(Charge on one electron $=1.6 \times 10^{-19} C$ )