SS2 Physics 3rd Term Questions and Answers

Physics Questions and Answers – SS2 – 3rd Term

Duration: 1hr 30mins

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Table of Contents – Weekly Scheme of Work

Week 1: Glass Prism
Week 2: Lenses
Week 3: Optical Instruments (Microscope & Telescope)
Week 4: Optical Instruments (Continued)
Week 5: Dispersion of White Light
Week 6: Dispersion of White Light (Continued)
Week 7: Sound Waves (Nature, Types)
Week 8: Sound Waves (Speed, Transmission)
Week 9: Resonance & Applications
Week 10–12: Revision & Examination

Section A: Objective Questions

A glass prism splits white light due to:
A. Reflection
B. Dispersion
C. Diffraction
D. Scattering
The angle between refracted and incident rays in a prism is the:
A. Angle of deviation
B. Angle of incidence
C. Angle of emergence
D. Apex angle
A convex lens always forms:
A. Virtual, upright image
B. Real, inverted image (under proper conditions)
C. No image
D. Virtual, inverted image
In a converging lens, the focal length depends on:
A. The object color
B. Surface curvature & refractive index
C. The object distance
D. The light source used
A simple microscope is an example of:
A. Camera
B. Telescope
C. Ophthalmoscope
D. Convex lens used close to the eye
A telescope uses lenses to:
A. Shine lasers
B. Collect faint distant light
C. Make colorful images
D. Reduce magnification
What splits white light into a spectrum?
A. Concave mirror
B. Prism
C. Polarizer
D. Convex lens
Dispersion causes:
A. Light slowing down equally in glass
B. Separation because of different refractive indices
C. Heat only
D. Sound
Red light in prism emerges at:
A. Larger angle than violet
B. Same angle
C. Smaller angle than violet
D. No deviation at all
Which colour refracts least in glass?
A. Violet
B. Green
C. Red
D. Blue
Sound waves are:
A. Transverse
B. Electromagnetic
C. Longitudinal
D. Magnetic
Speed of sound in air depends on:
A. Humidity and temperature
B. Light intensity
C. Colour of object
D. Air pressure only
In resonance, amplitude becomes:
A. Zero
B. Maximum
C. Negative
D. Constant
A tuning fork resonates at its:
A. Chemical frequency
B. Natural frequency
C. Combined frequency
D. Random value
Which cannot be seen in Newton’s Rings?
A. Concentric rings
B. Alternating dark/bright bands
C. Varying radii
D. Uniform dark field
Lens power is defined by:
A. 1/f (f in metres)
B. F × 2
C. f²
D. f × 100
Myopia correction uses:
A. Convex lens
B. Concave lens
C. Prism
D. Plane glass
Dispersion correct uses:
A. Water
B. Polarizer
C. Lens combination
D. Mirrors
Incident ray enters prism at 45°, emerges deviated by 60°. Apex is 30°. Angle of emergence is:
A. 30°
B. 45°
C. 15°
D. 75°
For a thin lens formula 1/f = 1/u + 1/v, u is:
A. Focal length
B. Image distance
C. Object distance
D. Thickness
Telescope resolution improved by:
A. Increasing aperture
B. Lengthening eyepiece only
C. Changing eyepiece colour
D. Cooling the lenses
Concave lens always forms:
A. Real inverted image
B. Virtual upright image
C. No image
D. Real upright image
Image in magnifying glass is:
A. Real, enlarged
B. Virtual, enlarged
C. Virtual, same size
D. Real, same size
Dispersion arises due to:
A. Same refractive index
B. Different refractive index for each colour
C. Constant speed in glass
D. Energy loss
Vibration causing resonance needs to match:
A. Any frequency
B. Natural frequency of object
C. Double natural frequency
D. Electromagnetic frequency
Sound waves do not travel in:
A. Vacuum
B. Solid
C. Liquid
D. Gas
Loudness perceived depends on:
A. Wavelength
B. Frequency
C. Amplitude
D. Pitch
Pitch depends on:
A. Wave amplitude
B. Frequency
C. Medium only
D. Temperature
In optical instrument, lenses are used to:
A. Bend light for magnification or focusing
B. Generate electricity
C. Produce sound
D. Block dust
Dispersion is reversed by:
A. Single convex lens
B. Second prism inverted
C. Concave mirror
D. Grating
Refraction at surface is described by:
A. Newton’s 1st law
B. Snell’s law
C. Pythagoras’ theorem
D. Ohm’s Law
Critical angle arises when refracted ray travels:
A. Normal
B. Along boundary
C. Away from interface
D. At 90°
TIR occurs when incident angle is:
A. Less than critical
B. Equal to Snell’s limit
C. Greater than critical
D. Zero
Speed of sound in solids is:
A. Less than in air
B. Greater than in air
C. Same as water
D. Zero
Beats occur due to interference of:
A. Two sounds of slightly different freqs
B. Sound and light
C. Two identical frequencies
D. Light interference
Node in standing wave is a point of:
A. Maximum amplitude
B. Minimum amplitude
C. Zero motion
D. Vibration transfer
Antinode has:
A. No vibration
B. Maximum vibration
C. Constant vibration
D. Vibration zero
Lenses in camera act as:
A. Concave only
B. Convex only
C. Plane glass
D. Prism
Colour separation in soap film is due to:
A. Dispersion only
B. Thin-film interference
C. Diffraction only
D. Sound waves
Echo occurs due to:
A. Dispersion
B. Reflection of sound
C. Refraction of sound
D. Diffraction

Section B: Theory Questions

Glass prism
Explain dispersion of light in a glass prism. Derive the expression for angle of deviation in a thin prism.
Lenses
A converging lens forms an image 15 cm from lens for an object 10 cm away. Calculate focal length and magnification.
Microscope
Describe the construction and working of a compound microscope. How does changing the eyepiece affect magnification?
Telescope
Compare astronomical and terrestrial telescopes, including lenses used and image orientation.
Dispersion
Why does violet light deviate more than red in glass? Explain using wave-particle and refractive index perspective.
Sound wave properties
Derive formula for the speed of sound in air using kinetic theory or Newton-Laplace equation.
Resonance
Explain resonance in air columns. Describe experiment to find the speed of sound using resonance tube.
Critical angle and total internal reflection
Derive critical angle for air-glass interface. Give two real-life applications.
Beats and interference
Explain formation of beats when two waves of nearly equal frequency superpose. Derive formula for beat frequency.
Doppler effect
Derive the expression for frequency shift when source approaches a stationary observer. Give real-world example.

Section C: Theory Questions

Glass prism
Explain dispersion of light in a glass prism. Derive the expression for angle of deviation in a thin prism.
Lenses
A converging lens forms an image 15 cm from lens for an object 10 cm away. Calculate focal length and magnification.
Microscope
Describe the construction and working of a compound microscope. How does changing the eyepiece affect magnification?
Telescope
Compare astronomical and terrestrial telescopes, including lenses used and image orientation.
Dispersion
Why does violet light deviate more than red in glass? Explain using wave-particle and refractive index perspective.

Section D: Theory Answers

Glass Prism

Dispersion:
When white light enters a glass prism, it splits into its constituent colors. This occurs because each wavelength is refracted by a different amount violet bends the most and red bends the least due to their different refractive indices.

Deviation Derivation (Thin Prism Approximation):

For a thin prism of apex A and small angles, total deviation δ≈(μ−1)A, where μ is the refractive index.

2. Lenses

Given ,
Use thin lens formula:

1/f = 1/u + 1/v = 1/10 + 1/15 = 1.5+1/15 = 2.5/15 = 1/6

Magnification:

So,

Magnification

3. Microscope

Construction:
Two lenses objective and eyepiece are aligned coaxially.

Working:
The objective lens forms a real, inverted, magnified image just outside its focal point. This image serves as the object for the eyepiece, which acts as a magnifier.

Eyepiece effect:Using a shorter focal length eyepiece increases total magnification but narrows field of view.

4. Telescope

Astronomical Telescope: Uses two convex lenses, producing an inverted image, suitable for observing distant celestial bodies.
Terrestrial Telescope: Adds an erecting lens system to correct image orientation.

Comparison:
Terrestrial telescopes are more complex but produce upright images, making them suitable for Earth-based use.

5. Dispersion of White Light

Why violet deviates most:
Glass has a higher refractive index for shorter wavelengths (violet), which leads to greater slowing and more refraction.

Wave-particle view:
Shorter wavelengths interact more with the glass molecules, causing them to bend more.

Conclusion

Revise all topics from Weeks 1–9 thoroughly optics and sound are core to SS2 Physics. Practice both objective and theory questions for deeper mastery. Stay consistent, maintain academic integrity, and approach your exams with confidence and discipline.

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