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Physics

Chapter 1 - Electric Current, Ohms Law and Kirchhoffs Laws

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Chapter 2 - Magnetic Effects of Electric Current and Measuring Instruments

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Chapter 3 - Electromagnetic Induction and AC Dynamo and Transformer

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Chapter 4 - Alternating Current AC Circuits

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Chapter 5 - Dual Nature of Wave and Particle

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Chapter 6 - Atomic Spectra and X-Rays

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Chapter 7 - Lasers and Principles

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Chapter 8 - Modern Electronics and Semiconductors

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Quiz

Lesson 4 Quiz: The Electric Transformer and Electric Motor (DC Motor)

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1.
STEM Semiconductor Electronics Problem 17: How is a p-type semiconductor crystal produced from pure intrinsic silicon?
By heating pure silicon above 1,000°C without impurities
By doping with pentavalent Phosphorus atoms
By doping the silicon crystal with trivalent impurity atoms (such as Boron or Aluminum), creating positive holes as majority carriers
By cooling silicon to absolute zero Kelvin
2.
STEM AC Transformer Problem 7: An ideal step-down transformer connected to a 220 V mains supply delivers power to a 12 V, 24 W lamp. What is the current flowing in the primary coil?
2.0 A
0.109 A
0.545 A
1.5 A
3.
Absolute zero temperature (0 Kelvin or -273.15 °C) is defined physically as the theoretical temperature at which:
The volume and pressure of an ideal gas theoretically extrapolate to zero and translational molecular motion reaches its quantum minimum
Atmospheric air completely combusts
Water reaches its maximum density
All liquids solidify into glass
4.
STEM Physics Problem 15: A copper wire of resistance 8.0 Ω is drawn out uniformly so that its length increases to three times its original value. Assuming constant mass and density, what is the new resistance of the wire?
24.0 Ω
2.67 Ω
16.0 Ω
72.0 Ω
5.
STEM Kirchhoff's Laws Problem 17: In a closed circuit junction, currents I1 = 2 A and I2 = 3 A flow toward junction A, while I3 = 1 A flows away. According to Kirchhoff's First Law (KCL), what is the magnitude and direction of the remaining current I
4 A flowing away from junction A
6 A flowing away from junction A
4 A flowing toward junction A
2 A flowing toward junction A
6.
STEM Alternating Current Dynamo Problem 37: An AC generator coil of 100 turns and area 0.05 m2 rotates at 3,000 rpm in a uniform magnetic field of 0.14 T. What is the maximum electromotive force (EMF_max) generated? (Use π = 22/7)
110 V
440 V
220 V
311 V
7.
STEM Alternating Current Dynamo Problem 6: An AC generator coil of 100 turns and area 0.05 m2 rotates at 3,000 rpm in a uniform magnetic field of 0.14 T. What is the maximum electromotive force (EMF_max) generated? (Use π = 22/7)
220 V
311 V
440 V
110 V
8.
STEM Semiconductor Electronics Problem 30: How is a p-type semiconductor crystal produced from pure intrinsic silicon?
By doping the silicon crystal with trivalent impurity atoms (such as Boron or Aluminum), creating positive holes as majority carriers
By cooling silicon to absolute zero Kelvin
By heating pure silicon above 1,000°C without impurities
By doping with pentavalent Phosphorus atoms
9.
The hydrostatic pressure exerted by a static homogeneous liquid of density rho at depth h beneath its free surface is expressed by:
P = rho * h / g
P = rho * g * h
P = rho * g / h
P = 1/2 rho * g * h2
10.
STEM AC Transformer Problem 42: An ideal step-down transformer connected to a 220 V mains supply delivers power to a 12 V, 24 W lamp. What is the current flowing in the primary coil?
2.0 A
0.545 A
1.5 A
0.109 A
11.
STEM Physics Problem 31: A copper wire of resistance 8.0 Ω is drawn out uniformly so that its length increases to three times its original value. Assuming constant mass and density, what is the new resistance of the wire?
24.0 Ω
2.67 Ω
72.0 Ω
16.0 Ω
12.
STEM Modern Physics Laser Problem 29: What fundamental condition is strictly required to achieve laser amplification via stimulated emission?
Population inversion, where the number of atoms in the metastable excited state exceeds that in the lower energy state
Complete absence of resonant optical mirrors
High electrical resistance in the discharge tube
Thermal equilibrium where ground state atoms dominate
13.
STEM AC Transformer Problem 4: An ideal step-down transformer connected to a 220 V mains supply delivers power to a 12 V, 24 W lamp. What is the current flowing in the primary coil?
0.109 A
2.0 A
1.5 A
0.545 A
14.
STEM Kirchhoff's Laws Problem 10: In a closed circuit junction, currents I1 = 2 A and I2 = 3 A flow toward junction A, while I3 = 1 A flows away. According to Kirchhoff's First Law (KCL), what is the magnitude and direction of the remaining current I
2 A flowing toward junction A
4 A flowing away from junction A
4 A flowing toward junction A
6 A flowing away from junction A
15.
STEM Kirchhoff's Laws Problem 41: In a closed circuit junction, currents I1 = 2 A and I2 = 3 A flow toward junction A, while I3 = 1 A flows away. According to Kirchhoff's First Law (KCL), what is the magnitude and direction of the remaining current I
4 A flowing away from junction A
4 A flowing toward junction A
6 A flowing away from junction A
2 A flowing toward junction A
16.
STEM AC Transformer Problem 11: An ideal step-down transformer connected to a 220 V mains supply delivers power to a 12 V, 24 W lamp. What is the current flowing in the primary coil?
2.0 A
1.5 A
0.545 A
0.109 A
17.
STEM Magnetic Force Problem 32: A straight conductor of length 0.50 m carries a current of 4.0 A in a uniform magnetic field of flux density 0.20 T. What is the magnetic force acting on the wire when it is inclined at 30° to the field lines?
0.346 N
0.10 N
0.40 N
0.20 N
18.
STEM Magnetic Force Problem 11: A straight conductor of length 0.50 m carries a current of 4.0 A in a uniform magnetic field of flux density 0.20 T. What is the magnetic force acting on the wire when it is inclined at 30° to the field lines?
0.346 N
0.40 N
0.20 N
0.10 N
19.
STEM AC Transformer Problem 28: An ideal step-down transformer connected to a 220 V mains supply delivers power to a 12 V, 24 W lamp. What is the current flowing in the primary coil?
2.0 A
1.5 A
0.545 A
0.109 A
20.
STEM Physics Problem 23: A copper wire of resistance 8.0 Ω is drawn out uniformly so that its length increases to three times its original value. Assuming constant mass and density, what is the new resistance of the wire?
16.0 Ω
2.67 Ω
24.0 Ω
72.0 Ω
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