Numerical Problems for Practice – Current electricity

  1. At room temperature (27 oC) resistance of a heating element is 100 ohm. What is the temperature of the element if the resistance is found to be 117 ohm. Given, temperature coeff. of resistance of the material is 1.70 x 10 -14 oC-1
  2. The ends of a resistance are connected to 19 cells in series, each of resistance 0.1 ohm. The current is found to be 2A. The number of cells is reduced to 15 and an extra resistance of 9.5 ohm is connected in series to the given resistance. The current becomes half. Find the given resistance and the emf of each cell.