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

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, $$e=1.6 \times 10^{-19} \mathrm{C}$$]

When a metal conductor connected to left gap of a meter bridge is heated, the balancing point

A wire of a certain material is stretched slowly by $$10 \%$$. Its new resistance and specific resistance becomes respectively