$(a)$ Resistivity of iron is $10 \times 10^{-8} \;\Omega m$ and of mercury is $94 \times 10^{-8}\; \Omega m$. Which among iron and mercury is a better conductor ? Give reason.
$(b)$ Resistivity of a material $A$ is in the range of $10^{10}-10^{\text {14 }} \;\Omega m$ while that of $B$ is in the range of $10^{-6}-10^{-8} \;\Omega$ m. Which of the two will behave as an insulator and why?
A child has drawn the electric circuit to study Ohm’s law as shown in Figure. His teacher told that the circuit diagram needs correction. Study the circuit diagram and redraw it after making all corrections.
Three resistors of $5\, \Omega, 10\, \Omega$ and $15\, \Omega$ are connected in series and the combination is connected to battery of $30\, V$. Ammeter and voltmeter are connected in the circuit. Draw a circuit diagram to connect all the devices in proper correct order. What is the current flowing and potential difference across $10\, \Omega$ resistance ?
Read the following statements carefully and write whether the statement is true or false
$(i)$ The quantity of charge flowing past a point multiplied by time is current.
$(ii)$ The flow of charge through a conducting wire connected to a cell is the result of chemical reaction inside the cell
$(iii)$ The resistivity of all pure metals increases with increase in temperature.
$(iv)$ Ohm's law is a relation between the power used in a circuit to the current and the potential difference.
$(v)$ $A$ series circuit has only one conducting path for the electrons that move through it; a parallel circuit has multiple conducting paths.
$(vi)$ A conducting wire offers resistance to the flow of electrons because electrons repel each other in the wire.
Define power. State the difference between $1$ watt and $1$ watt hour. Establish the relationship between unit of electric energy and $SI$ unit of energy. An electric heater rated $1000\, W / 220 \,V$ operates $2$ hours daily. Calculate the cost of energy to operate for $30$ days at the rate of ₹ $5.00$ per $k W h$