Power from a Cell

  • Terminal PD of a cell of emf 4 V is zero when current from it is 10 A. Internal resistance of the cell is
    A) 0.1 Ω B) 0.2 Ω C) 0.4 Ω D) 1 Ω
  • Terminal PD of a cell is 5 V when 2A of current is drawn from it and 8V when current of 4A is used to charge it. Internal resistance resistance of the cell is
    A) 0.1 Ω B) 0.2 Ω C) 0.5 Ω D) 1 Ω
  • Two cells of equal emfs but different internal resistances of $r_1$ and $r_2$ are connected in series . An external resistance $R$ is connected in series with two sources of e.m.f.
    A) $R = (r_1-r_2)$, for terminal potential difference to be zero across source 1.
    B) $R = √{r_1r_2}$, for terminal potential difference to be zero across both sources.
    C) $R = r_2^2\/r_1$, for terminal potential difference to be zero across source 2.
    D) $R = r_1^2\/r_2$, for terminal potential difference to be zero across source 1.
  • Maximum power a cell of emf E and internal resistance r can provide any external resistance is
    A) $E^2\/r$ B) $E^2\/2r$ C) $E^2\/3r$ D) $E^2\/4r$
  • Current from a cell of emf 4V and internal resistance 0.1 Ω, when 30 W power is delivered to an external resistance is
    A) 10 A B) 30 A C) Both D) None