What happens to the resistance of a conductor when its temperature is increased?

$(a)$ What are the values of $mA$ and $\mu A$ in terms of Ampere $(A)$?
$(b)$ Draw the symbols of a battery and a rheostat.

Out of the two,a toaster of $1\, kW$ and an electric heater of $2\, kW$,which has a greater resistance?

You are given three resistors of $10\, \Omega, 10\, \Omega, 20\, \Omega$,a battery of emf $2.5\, V$,a key,an ammeter,and a voltmeter. Draw a circuit diagram showing the correct connections of the given components such that the voltmeter gives a reading of $2.0\, V$.

$A$ potential difference $V$ is applied across a conductor of length $L$ and diameter $D$. How is the resistance $R$ of the conductor affected,when in turn $(i)$ $V$ is halved,$(ii)$ $L$ is halved,and $(iii)$ $D$ is doubled? Justify your answer in each case.

What do you mean by the heating effect of electric current? Explain the production of heat in a resistor by the flow of electric current through it. Name two devices based on the heating effect of current.