Physics, HSSC-Punjab First Year. This chapter is split into 36 topics and has
834 practice questions. The topics covered are listed below, followed by
10 free sample questions from the chapter.
Topics in this chapter
Brewster (polarizing) angle from the refractive index24 questions
Polarization: what it is and why it needs transverse waves24 questions
Stress analysis of materials: photoelasticity20 questions
Malus's law: intensity transmitted by an analyzer24 questions
Angle of refraction when the reflected light is fully polarized24 questions
Rotating an analyzer: angles for a given drop in intensity24 questions
Polarized sunglasses, glare and sky photography21 questions
Linear, circular and elliptical polarization24 questions
Optical activity and optically active substances24 questions
Methods of producing polarized light21 questions
Light-years and the travel time of gravitational waves25 questions
Malus's law: statement, derivation and extreme cases25 questions
Frequency and wavelength of gravitational waves24 questions
Malus's law: finding the angle between the axes21 questions
Formulae and units used with polarization and gravitational waves20 questions
Gravitational waves: meaning and the idea of space-time25 questions
Unpolarized light through a pair of polarizing filters24 questions
Space-time distortion and tidal forces21 questions
How an interferometer detects a gravitational wave23 questions
Polarization by reflection and Brewster's law28 questions
Unpolarized light and its sources20 questions
A stack of polarizing sheets each rotated by a fixed angle20 questions
Refractive index from the polarizing angle24 questions
Prediction and first detection of gravitational waves24 questions
Importance and applications of polarization25 questions
Virgo and other facts about gravitational wave observatories22 questions
Assertion and reason questions on polarization and gravitational waves22 questions
Tiny length changes in an interferometer arm20 questions
Characteristics of gravitational waves and orbital eccentricity20 questions
Amplitude of the transmitted wave: A = A0 cos(theta)24 questions
Production and detection of plane polarized light: polarizer and analyzer24 questions
Brewster angle at an interface between two media24 questions
Percentage of intensity transmitted or blocked by an analyzer24 questions
Binary systems and the four basic types of gravitational waves25 questions
The interferometer and the components of LIGO27 questions
Concept questions in the style of the chapter exercise23 questions
Sample questions: Physical Optics and Gravitational Waves
10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.
Q1. Which of the following would be unpolarized light?
A. Light from a laser beam after a polarizing filter
B. Light reflected from glass at the polarizing angle
C. Light that has passed through a polaroid sunglass lens
D. Light from a candle flame reaching the eye directly(correct answer)
Answer: D.A flame emits light from many atoms with randomly oriented vibrations, while the other three sources are polarized by a filter or by reflection.
Q2. The sky light is polarized partially due to:
A. scattering of sunlight by small particles and molecules in the atmosphere(correct answer)
B. absorption of ultraviolet light by the ozone layer only
C. reflection of sunlight from the surface of the Moon at night
D. emission of light by the distant stars in all directions
Answer: A.Light scattered by air molecules and particles becomes partially polarized (the book mentions scattering as a natural polarizing process).
Q3. A gravitational-wave event happened 1.3 × 10⁹ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 1.3 × 10⁹ years(correct answer)
B. 3.56 × 10⁶ years
C. 4.74 × 10¹¹ years
D. 1.24 × 10¹⁰ years
Answer: A.A light-year is the distance light travels in one year, so a distance of 1.3 × 10⁹ light-years needs 1.3 × 10⁹ years at the speed of light.
Q4. A gravitational-wave event happened 2 × 10⁹ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 1.9 × 10¹⁰ years
B. 2 × 10⁹ years(correct answer)
C. 7.3 × 10¹¹ years
D. 5.48 × 10⁶ years
Answer: B.A light-year is the distance light travels in one year, so a distance of 2 × 10⁹ light-years needs 2 × 10⁹ years at the speed of light.
Q5. A gravitational-wave event happened 5 × 10⁸ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 1.37 × 10⁶ years
B. 1.82 × 10¹¹ years
C. 5 × 10⁸ years(correct answer)
D. 4.75 × 10⁹ years
Answer: C.A light-year is the distance light travels in one year, so a distance of 5 × 10⁸ light-years needs 5 × 10⁸ years at the speed of light.
Q6. A gravitational-wave event happened 1 × 10⁹ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 3.65 × 10¹¹ years
B. 9.5 × 10⁹ years
C. 1 × 10⁹ years(correct answer)
D. 2.74 × 10⁶ years
Answer: C.A light-year is the distance light travels in one year, so a distance of 1 × 10⁹ light-years needs 1 × 10⁹ years at the speed of light.
Q7. A gravitational-wave event happened 3 × 10⁹ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 1.1 × 10¹² years
B. 8.22 × 10⁶ years
C. 3 × 10⁹ years(correct answer)
D. 2.85 × 10¹⁰ years
Answer: C.A light-year is the distance light travels in one year, so a distance of 3 × 10⁹ light-years needs 3 × 10⁹ years at the speed of light.
Q8. A gravitational-wave event happened 7.5 × 10⁸ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 2.05 × 10⁶ years
B. 7.12 × 10⁹ years
C. 2.74 × 10¹¹ years
D. 7.5 × 10⁸ years(correct answer)
Answer: D.A light-year is the distance light travels in one year, so a distance of 7.5 × 10⁸ light-years needs 7.5 × 10⁸ years at the speed of light.
Q9. A gravitational-wave event happened 1.8 × 10⁹ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 1.8 × 10⁹ years(correct answer)
B. 6.57 × 10¹¹ years
C. 1.71 × 10¹⁰ years
D. 4.93 × 10⁶ years
Answer: A.A light-year is the distance light travels in one year, so a distance of 1.8 × 10⁹ light-years needs 1.8 × 10⁹ years at the speed of light.
Q10. A gravitational-wave event happened 2.5 × 10⁸ light-years away. Since the waves travel at the speed of light, how many years did they take to reach us?
A. 685000 years
B. 2.38 × 10⁹ years
C. 9.12 × 10¹⁰ years
D. 2.5 × 10⁸ years(correct answer)
Answer: D.A light-year is the distance light travels in one year, so a distance of 2.5 × 10⁸ light-years needs 2.5 × 10⁸ years at the speed of light.