State two reasons why the key in the circuit should be opened when reading
are not taken.

1) If a cell or battery is used, the key in the circuit should be left open so as not to drain the battery or cell.

2) Also, leaving the key closed causes current to flow through the circuit, which also causes the temperature of the circuit to increase. Since the resistance of most metals increases with an increase in temperature, the resistance of the circuit will increase, which will then affect the integrity of the whole experiment.

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.