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The figure below shows an electrical circuit including three switches, S1, S2, S3 and three identical lamps LI, L2,L3. A constant potential difference is applied across X and Y.

i).Other than L1, state the lamp that will light when S1 and S2 are closed.
(ii) How does the brightness in L1 in (i) above compare with its brightness when all the switches are closed?
(iii) Explain the observation in (ii) above.

Answer Text:
i).L2
ii).It is brighter when all the switches are closed.
iii).When all the switches are closed the total resistance is less.