2. Write the four characteristics of an image formed by a plane mirror.
[2]
3. Define the principal focus of a concave mirror. Why is the focus of a convex mirror considered
virtual?
[2]
4. State Snell's Law of refraction. Express it mathematically. Under what condition does a ray of light
pass through a medium without bending?
[3]
5. Explain why a convex mirror is preferred as a rear-view mirror in vehicles.
[2]
6. Differentiate between real and virtual images.
[2]
7. Define the power of a lens. What is its SI unit? One student uses a lens of focal length +50 cm and
another of -50 cm. What is the nature of the lens and its power in each case?
[3]
8. Why do we prefer a convex mirror as a shop security mirror?
[1]
SECTION B: THE HUMAN EYE & COLOURFUL WORLD
9. Explain the formation of a Rainbow with the help of a labeled diagram. Name the three phenomena
involved in its formation.
[3]
10. Why do stars twinkle but planets do not? Explain in detail.
[3]
11. Why does the sun appear visible to us about 2 minutes before the actual sunrise and 2 minutes after
the actual sunset?
[3]
12. What is atmospheric refraction? List two phenomena observed due to atmospheric refraction.
[2]
13. Why is the colour of the clear sky blue?
[2]
14. What is the Tyndall effect? Give one example observed in daily life.
[2]
15. Explain why the planets do not twinkle.
[2]
16. Why are danger signal lights red in colour?
[1]
17. What is dispersion of white light? Name the component of white light that deviates the least and the
most while passing through a glass prism.
[2]
SECTION C: ELECTRICITY & MAGNETISM (THEORETICAL)
18. State Ohm's Law. Draw a circuit diagram to verify this law.
[3]
19. List the factors on which the resistance of a conductor depends. How does the resistance change if
(i) Length is doubled, (ii) Area of cross-section is doubled?
[3]
20. Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
[2]
21. State Joule's Law of Heating.
[2]
22. Why is the series arrangement not used for domestic circuits? Give three reasons.
[3]
23. What is the function of an earth wire? Why is it necessary to earth metallic appliances?
[2]
24. Draw the pattern of magnetic field lines around a current-carrying straight conductor. Apply the
Right-Hand Thumb Rule to find the direction of magnetic field.
[3]
25. List the properties of magnetic field lines. Why do two magnetic field lines never intersect each
other?
