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.

In an atom electrons revolve around the nucleus along a path of radius $$0.72\mathop A\limits^o$$ making $$9.4 \times 10^{18}$$ revolutions per second. The equivalent currents is [given, $$e=1.6 \times 10^{-19} \mathrm{C}$$]