Question
(a) Identify the laws of conservation that are represented by Kirchhoff’s circuit laws. [2]
(b) A cell is connected to an ideal voltmeter, a switch S and a resistor R. The resistance
of R is 4.0Ω.
When S is open the reading on the voltmeter is 12V. When S is closed the voltmeter
reads 8.0V.
(i) State the emf of the cell. [1]
(ii) Deduce the internal resistance of the cell. [2]
(c) The voltmeter is used in another circuit that contains two secondary cells.
Cell A has an emf of 10V and an internal resistance of 1.0Ω. Cell B has an emf of 4.0V
and an internal resistance of 2.0Ω.
Calculate the reading on the voltmeter. [3]
(d) Electricity can be generated using renewable resources.
(i) Outline why electricity is a secondary energy source. [1]
(ii) Some fuel sources are renewable. Outline what is meant by renewable. [1]
(e) (i) A fully charged cell of emf 6.0V delivers a constant current of 5.0A for a time of
0.25 hour until it is completely discharged.
The cell is then re-charged by a rectangular solar panel of dimensions
0.40m × 0.15m at a place where the maximum intensity of sunlight
is 380Wm−2.
The overall efficiency of the re-charging process is 18%.
Calculate the minimum time required to re-charge the cell fully. [3]
(ii) Outline why research into solar cell technology is important to society. [1]
Answer/Explanation
Ans.
