9.1 A simplified diagram of a DC electric motor is shown below - NSC Physical Sciences - Question 9 - 2023 - Paper 1
Question 9
9.1 A simplified diagram of a DC electric motor is shown below.
9.1.1 Write down the name of component A.
9.1.2 State the energy conversion that takes place in th... show full transcript
Worked Solution & Example Answer:9.1 A simplified diagram of a DC electric motor is shown below - NSC Physical Sciences - Question 9 - 2023 - Paper 1
Step 1
9.1.1 Write down the name of component A.
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Answer
The name of component A is the Split Ring or Commutator.
Step 2
9.1.2 State the energy conversion that takes place in the motor.
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Answer
The energy conversion that takes place in the motor is from electrical energy to mechanical (kinetic) energy.
Step 3
9.1.3 In which direction will the coil rotate? Choose from CLOCKWISE or ANTICLOCKWISE.
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Answer
The coil will rotate CLOCKWISE.
Step 4
9.1.4 State TWO changes that can be made to the motor for the coil to rotate faster.
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Answer
Increase the strength of the magnetic field by using stronger magnets.
Increase the current supplied to the motor by using a higher voltage battery.
Step 5
9.2.1 Define the term root mean square current.
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Answer
Root mean square current (I_rms) is the effective value of alternating current (AC) that dissipates the same amount of energy/heat as an equivalent direct current (DC).
Step 6
9.2.2 When switch S1 is CLOSED and switch S2 is OPEN, the maximum current through the circuit is 3.6 A. Calculate the root mean square current in the circuit.
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Answer
To calculate the root mean square current, use the formula:
I_{rms} = rac{I_{max}}{ ext{√2}}
Thus,
= 2.55 ext{ A}$$
Step 7
9.2.3 When S1 is OPEN and S2 is CLOSED, the root mean square current in the circuit is 2.62 A. Calculate the energy consumed by the toaster in two minutes.
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Answer
To calculate the energy consumed by the toaster, we can use the formula:
W=Pimest
where
P (power) can be calculated using:
P=VrmsimesIrms
Substituting, we find:
= 576.4 ext{ W}$$
Next, to find the energy consumed in two minutes (120 seconds):
$$W = 576.4 ext{ W} imes 120 ext{ s} = 69,168 ext{ J}$$
