9.1 A simplified diagram of an electrical machine is shown below - NSC Physical Sciences - Question 9 - 2020 - Paper 1
Question 9
9.1 A simplified diagram of an electrical machine is shown below.
Is this machine a DC motor or a DC generator?
Write down the energy conversion that takes place w... show full transcript
Worked Solution & Example Answer:9.1 A simplified diagram of an electrical machine is shown below - NSC Physical Sciences - Question 9 - 2020 - Paper 1
Step 1
Is this machine a DC motor or a DC generator?
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This machine is a DC motor. A DC motor converts electrical energy into mechanical energy, while a DC generator does the opposite.
Step 2
Write down the energy conversion that takes place while this machine is in operation.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The energy conversion that takes place is from electrical energy to mechanical kinetic energy.
Step 3
Write down the name of component A in the diagram.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Component A is the split ring commutator.
Step 4
In which direction will the coil, shown in the diagram above, rotate? Choose from CLOCKWISE or ANTICLOCKWISE.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The coil will rotate in the ANTICLOCKWISE direction.
Step 5
Define the term rms voltage.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The rms voltage (or root mean square voltage) is the AC voltage/potential difference that dissipates the same amount of energy/heat as an equivalent DC voltage.
Step 6
Calculate the resistance of the device.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The resistance (R) can be calculated using the formula:
R=PV2
For this device,
R=2002202=242Ω.
Step 7
Calculate the energy dissipated by the device in 10 minutes.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Energy (W) can be calculated using the formula:
W=P⋅t
Where P = 200 W and t = 10 minutes = 600 seconds. Hence,
W=200×600=120,000J.
