A moving coil galvanometer is converted into an ammeter of range 0 to $$5 \mathrm{~mA}$$. The galvanometer resistance is $$90 \Omega$$ and the shunt resistance has a value of $$10 \Omega$$. If there are 50 divisions in the galvanometer-turned-ammeter on either sides of zero, its current sensitivity is

A charged particle is moving in an electric field of $$3 \times 10^{-10} \mathrm{Vm}^{-1}$$ with mobility $$2.5 \times 10^6 \mathrm{~m}^2 / \mathrm{V}-\mathrm{s}$$, its drift velocity is

Wire bound resistors are made by winding the wires of an alloy of

10 identical cells each potential $$E$$ and internal resistance $$r$$ are connected in series to form a closed circuit.

Determine the potential difference across three cells using an ideal voltmeter.