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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 1 Quiz: Laser Physics, Population Inversion and the Helium-Neon Laser

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1.
STEM Alternating Current Dynamo Problem 40: 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)
311 V
440 V
110 V
220 V
2.
STEM Physics Problem 4: 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?
2.67 Ω
72.0 Ω
24.0 Ω
16.0 Ω
3.
STEM Modern Physics Laser Problem 8: What fundamental condition is strictly required to achieve laser amplification via stimulated emission?
Thermal equilibrium where ground state atoms dominate
Population inversion, where the number of atoms in the metastable excited state exceeds that in the lower energy state
High electrical resistance in the discharge tube
Complete absence of resonant optical mirrors
4.
STEM Semiconductor Electronics Problem 8: How is a p-type semiconductor crystal produced from pure intrinsic silicon?
By heating pure silicon above 1,000°C without impurities
By cooling silicon to absolute zero Kelvin
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
5.
STEM Physics Problem 34: 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?
72.0 Ω
16.0 Ω
24.0 Ω
2.67 Ω
6.
If both inductance \(L\) and capacitance \(C\) in a resonant circuit are doubled, the resonance frequency will:
B) Quadruple
C) Decrease to half its original value
D) Remain unchanged
A) Double
7.
STEM Alternating Current Dynamo Problem 24: 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
8.
STEM Alternating Current Dynamo Problem 5: 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)
311 V
440 V
220 V
110 V
9.
STEM AC Transformer Problem 3: 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
0.545 A
1.5 A
2.0 A
10.
STEM Magnetic Force Problem 13: 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
11.
STEM Magnetic Force Problem 29: 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
12.
STEM Alternating Current Dynamo Problem 34: 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)
311 V
440 V
220 V
110 V
13.
STEM Compton Effect Problem 14: In the Compton scattering effect, when a high-energy X-ray photon collides with a free stationary electron, which change occurs to the scattered photon?
Its mass increases while kinetic energy decreases
Its frequency decreases, its wavelength increases, and its speed remains strictly c (speed of light)
Its speed decreases significantly while wavelength remains constant
Its frequency increases and energy increases
14.
STEM Kirchhoff's Laws Problem 6: 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 I4
6 A flowing away from junction A
2 A flowing toward junction A
4 A flowing away from junction A
4 A flowing toward junction A
15.
STEM Compton Effect Problem 35: In the Compton scattering effect, when a high-energy X-ray photon collides with a free stationary electron, which change occurs to the scattered photon?
Its frequency increases and energy increases
Its mass increases while kinetic energy decreases
Its speed decreases significantly while wavelength remains constant
Its frequency decreases, its wavelength increases, and its speed remains strictly c (speed of light)
16.
STEM Modern Physics Laser Problem 34: 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
17.
STEM Physics Problem 27: 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
24.0 Ω
72.0 Ω
2.67 Ω
18.
The mechanical advantage (eta) of an ideal hydraulic press equals all of the following ratios EXCEPT:
Work done by the large piston / Work done on the small piston > 1
Distance moved by the small piston / Distance moved by the large piston (y1 / y2)
Area of the large piston / Area of the small piston (A / a)
Force on the large piston / Force on the small piston (F / f)
19.
STEM Magnetic Force Problem 3: 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
20.
The pressure of a gas trapped inside an incandescent light bulb is 0.8 atm at room temperature (27 °C). When the bulb operates, the filament heats the gas to 327 °C at constant volume. The operational pressure is:
1.6 atm
0.96 atm
1.2 atm
2.4 atm
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