When the hair straighteners reach normal operating temperature, an LED turns on.
When the hair straighteners reach normal operating temperature, an LED turns on.
i- Draw the circuit symbol for an LED in the box.
[1 mark]
SOLUTION
Figure 13 shows the circuit diagram for the hair straighteners. box
Each resistor represents a heating element.
The power output of the hair straighteners can be changed by closing different switches.
ii- Why do the hair straighteners not turn on when only switch S2 is closed?
[1 mark]
SOLUTION
Because isnt close, the switch
iii- The hair straighteners have a maximum power output of 120 W.
The energy transferred to the hair straighteners to reach normal operating temperature is 3.6 kJ.
Calculate the time taken for the hair straighteners to reach normal operating temperature when operating at maximum power.
Use the Physics Equations Sheet.
[4 marks]
SOLUTION
iv- Figure 14 shows the hair straighteners circuit with switch S1 closed.
Switch S2 and switch S3 are then closed at the same time.
Explain what happens to the power output of the power supply.
[3 marks]
SOLUTION
The total resistance of the circuit decreases as the resistors are sonnected in parallel.
Thus, the current would increase.
Thus power would also increase. (From P=VI, P and I are proportional to each other that’s why power also increases.)
