ICSE Class 10 Physics Flashcards

24 sample cards from the Physics deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. Give two practical applications/examples of total internal reflection.

   Examples: optical fibres, brilliance/sparkle of diamonds, mirage, and use of a 45-degree-45-degree-90-degree total reflecting prism in periscopes/binoculars.

2. What is a prism and what does it do to white light?

   A prism is a transparent medium bounded by inclined refracting surfaces. It disperses white light into its constituent colours (spectrum) because different colours bend by different amounts.

3. Define dispersion of light. Which colour deviates most and which least?

   Dispersion is the splitting of white light into its seven constituent colours on passing through a prism. Violet deviates the most; red deviates the least.

4. What is a convex lens? What type of image can it form?

   A convex (converging) lens is thicker at the centre and converges parallel rays to a focus. It can form real, inverted images and also virtual, erect, magnified images (when object is within the focal length).

5. Define focal length of a lens.

   The focal length is the distance between the optical centre of the lens and its principal focus.

6. State the relation between focal length (f) and power (P) of a lens, with units.

   Power P = 1 / f (with f in metres). SI unit of power: dioptre (D). 1 D = 1 m^-1.

7. What is the power of a converging lens versus a diverging lens (sign)?

   A converging (convex) lens has positive power; a diverging (concave) lens has negative power.

8. What is a spectrum? Name the seven colours in order from least to most deviated.

   A spectrum is the band of colours obtained when white light is dispersed. Order from least to most deviated: Red, Orange, Yellow, Green, Blue, Indigo, Violet (VIBGYOR is the reverse).

9. How does the refractive index of a medium depend on the colour (wavelength) of light?

   Refractive index is greater for shorter wavelengths; it is maximum for violet light and minimum for red light, so violet refracts/deviates more than red.

10. What is sound? Through which media can it travel?

    Sound is a form of energy that produces the sensation of hearing; it travels as longitudinal mechanical waves. It can travel through solids, liquids, and gases but NOT through vacuum.

11. Define an echo.

    An echo is the repetition of a sound caused by the reflection of sound waves from a hard, distant surface back to the listener.

12. What minimum distance from a reflecting surface is needed to hear a distinct echo? (speed of sound ~ 340 m/s)

    The reflecting surface must be at least about 17 metres away, because the ear can distinguish two sounds separated by at least 0.1 s and sound must travel to and fro.

13. Define infrasonic, audible, and ultrasonic sound by frequency range.

    Infrasonic: below 20 Hz. Audible (for humans): 20 Hz to 20,000 Hz. Ultrasonic: above 20,000 Hz.

14. What is the difference between loudness and pitch of a sound?

    Loudness depends on the amplitude of the wave (greater amplitude = louder). Pitch depends on the frequency (higher frequency = higher pitch/shriller sound).

15. Define resonance.

    Resonance is the phenomenon in which a body vibrates with maximum amplitude under the action of a periodic force whose frequency equals the body's natural frequency.

16. Define natural frequency and forced vibrations.

    Natural frequency is the frequency at which a body vibrates freely when disturbed. Forced vibrations are vibrations of a body under an external periodic force at a frequency different from its natural frequency.

17. State the relation between speed, frequency, and wavelength of a wave.

    Speed = frequency x wavelength (v = f lambda).

18. Give two practical applications of ultrasound.

    Applications: medical ultrasonography (imaging organs/foetus), SONAR for measuring sea depth, detecting flaws in metals, and cleaning delicate parts.

19. What is the timbre (quality) of a sound?

    Timbre or quality is the characteristic that distinguishes two sounds of the same loudness and pitch produced by different sources; it depends on the waveform (overtones present).

20. State Ohm's law and give its formula.

    At constant temperature, the current through a conductor is directly proportional to the potential difference across it. V = I R, where R is the resistance.

21. How do you calculate equivalent resistance of resistors in series and in parallel?

    Series: R = R1 + R2 + R3 + ... Parallel: 1/R = 1/R1 + 1/R2 + 1/R3 + ...

22. State the expression for electrical power in terms of V, I, and R.

    Power P = V I = I squared R = V squared / R.

23. State Joule's law of heating.

    The heat produced in a conductor is directly proportional to the square of the current (I^2), the resistance (R), and the time (t) for which current flows. H = I squared R t.

24. State the right-hand thumb rule for the magnetic field due to a current-carrying conductor, and Fleming's left-hand rule.

    Right-hand thumb rule: if the thumb points in the direction of current, the curled fingers give the direction of the magnetic field. Fleming's left-hand rule: thumb, forefinger, and middle finger held mutually perpendicular point to force (motion), field, and current respectively, giving the direction of force on a current-carrying conductor in a magnetic field.

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