7. The amount of current per unit area at all points across a cross section of a conductor is constant.
8. When a resistor is connected across the cell and it dies, the cell will give zero voltage.
9. If R₁ = 90 and R = 120 are in parallel, the total resistance R_total is given by: 1/R_total = 1/R₁ + 1/R = 1/90 + 1/120 = (4+3)/(4*3*90) = 7/360. Therefore, R_total = 360/7.
If the current going into the circuit is given as I, the total current through the circuit would be I_total = V/R_total = V/(360/7) = 7V/360, where V is the voltage across the external resistance.