$A$ wire of resistance $5 \, \Omega$ is bent in the form of a closed circle. What is the resistance between two points at the ends of any diameter of the circle?

$(a)$ What do the following symbols represent in a circuit? Write the name and one function of each.
$(b)$ Draw a schematic diagram of a circuit consisting of a battery of $12 \, V$,three resistors of $5 \, \Omega$,$10 \, \Omega$,and $20 \, \Omega$ connected in parallel,an ammeter to measure the total current through the circuit,and a voltmeter to measure the potential difference across the combination of resistors.
$(c)$ State any one advantage of connecting electrical devices in parallel with the mains instead of connecting them in series in a household circuit.

What are the factors on which the resistivity of a material depends?

You are given three bulbs of $25 \, W$,$40 \, W$,and $60 \, W$ marked at $220 \, V$. Which one of them has the lowest resistance?

How can we measure the potential difference across the ends of a conductor?

When a high resistance voltmeter is connected directly across an electric bulb,its reading is $2 \ V$. An electric cell is sending a current of $0.4 \ A$ (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 calculations. If a graph is plotted between $V$ and $I$,show the nature of the graph obtained.