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Course: American System Physics
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American System Physics

A Physics Toolkit

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Representing Motion

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Accelerated Motion

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Forces in One Dimension

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Displacement and Force in Two Dimensions

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Motion in Two Dimensions

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Gravitation

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Rotational Motion

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Momentum and Its Conservation

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Energy and Its Conservation

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Thermal Energy

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States of Matter

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Vibrations and Waves

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Sound

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Fundamentals of Light

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Reflection and Refraction

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Interference and Diffraction

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Electrostatics

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Electric Current and Circuits

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Magnetic Fields

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Electromagnetic Induction and Electromagnetism

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Quantum Theory and the Atom

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Solid-State Electronics

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Nuclear and Particle Physics

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Quiz

21.0 Electromagnetism: Induction, Generators, Transformers and Electromagnetic Waves – Check yourself

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Electromagnetism American Physics check yourself quiz: free practice for American System Physics. Work through this Electromagnetism American Physics check yourself quiz and get instant feedback on every answer. If you get stuck, review the 21.3 Transformers and Power Transmission — Notes lesson. More practice: American System Physics — all units. Syllabus: OpenStax free science textbooks.

  • Questions count: 17
  • Passing grade: B+
  • Time limit: 10 minutes
Start Quiz
1.
Transformers need
DC
AC
batteries
magnets only
2.
Step-down transformer: secondary voltage
higher
lower
same
zero
3.
Which statement best describes Transformer?
Changes AC voltage: Vs/Vp = Ns/Np.
Induced current opposes the change that produced it.
Coupled oscillating electric and magnetic fields travelling at c.
Separates ions by q/m ratio in fields.
4.
What is the output voltage of the ideal transformer shown?
Dr Dabour Hub Academy - figure 1
600 V
120 V
2.4 V
24 V
5.
For the grid in the diagram, why is transformer A used?
Dr Dabour Hub Academy - figure 2
To raise the voltage and lower the current, reducing I²R losses in the lines
To raise both voltage and current
To convert AC into DC
To lower the line voltage for safety
6.
Which conclusion fits the data in the table?
Output is proportional to secondary turns and about 98% of the ideal value
Output is exactly ideal
Output is inversely proportional to turns
Output is independent of turns
7.
An X-ray machine uses a transformer with 100 primary turns and 2000 secondary turns on 120 V AC. What is the output voltage?
6.0 V
2280 V
2400 V
120 V
8.
An ideal transformer steps 120 V down to 12 V and delivers 2.5 A. What current is drawn from the 120 V supply?
25 A
0.25 A
2.5 A
0.025 A
9.
Which pairing for a step-up transformer is correct?
Voltage increases - current increases
Ns < Np - voltage increases
Voltage increases - current decreases
Voltage decreases - current decreases
10.
A power line carries 1000 A. A transformer raises the voltage 50 times for the same power. By what factor does the I²R loss change?
It is divided by 50
It is divided by 2500
It is multiplied by 50
It is unchanged
11.
A line of resistance 2.0 Ω carries 150 A. What power is lost as heat?
300 W
75 W
45 kW
22.5 kW
12.
Using the table, the loss at 10 kV is _____.
500 W
5000 W
50 W
50 000 W
13.
To obtain 24 V from a 6 V AC supply using a primary of 250 turns, the number of secondary turns must be _____.
1000
62.5
6000
144
14.
If the transformer shown delivers 4.0 A from its secondary, the primary current is 20 A. True or false?
Dr Dabour Hub Academy - figure 3
False, it is 0.80 A
True
False, it is 4.0 A
False, it is 8.0 A
15.
In the diagram, transformer B is step-up because it is closer to the homes. True or false?
Dr Dabour Hub Academy - figure 4
True
False, B leaves the voltage unchanged
True only at night
False, B is step-down, reducing 275 kV to 120 V
16.
For the 1000-turn row of the table, the transformer is step-up with an ideal output of 240 V. True or false?
False, it is step-down
True
False, the ideal output is 60 V
False, the ideal output is 120 V
17.
A garden-light transformer with 1500 primary and 75 secondary turns reduces 240 V AC to 12 V. True or false?
False, it gives 4800 V
False, it gives 228 V
False, it gives 24 V
True
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Part of Electromagnetic Induction and Electromagnetism — see every lesson and quiz in this unit.
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