1. What is the near and far point of a normal eye?
2. Name the component of eye that is responsible for the adjustment of eyelens?
3. To an astronaut why does the sky appear dark instead of blue?
4. Why the star twinkle but not earth?
5. Draw the labelled diagram of human eye and explain the image formation?
6. What is power of accommodation? How ciliary muscles helps in accommodation?
7. Explain the function of
a. Iris
b. Pupil
c. Retina
8. Calculate the number of electrons constituting one coulomb of charge.
9. Define the unit of current.
10. What is meant by saying that the potential difference between two points is 1 V?
11. The potential difference between the terminals of an electric heater is 60 V when it draws a current of 4 A from the source. What current will the heater draw if the potential difference is increased to 120 V?
12. A wire of given material having length l and area of cross-section A has a resistance of 4. What would be the resistance of another wire of the same material having length l/2 and area of cross-section 2A?
13. Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
14. An electric lamp, whose resistance is 20 Ω, and a conductor of 4 resistance are connected to a 6 V battery Calculate (a) the total resistance of the circuit, (b) the current through the circuit, and (c) the potential difference across the electric lamp and conductor.
15. In the circuit diagram given in Fig. 12.10, suppose the resistors R1, R2 and R3 have the values respectively, which have been connected to a battery of 12 V. Calculate (a) the current through each resistor, (b) the total current in the circuit, and (c) the total circuit resistance.
16. What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?
17. What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance ?
18. An electric iron of resistance takes a current of 5 A. Calculate the heat developed in 30 s.
19. An electric refrigerator rated 400 W operates 8 hour/day. What is the cost of the energy to operate it for 30 days at Rs 3.00 per kW h?
20. How many resistors (in parallel) are required to carry 5 A on a 220 V line?
21. Compare the power used in the resistor in each of the following circuits: (i) a 6 V battery in series with and resistors, and (ii) a 4 V battery in parallel with and resistors.
22. An electric heater of resistance 8 draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
23. Why is the series arrangement not used for domestic circuits?
24. A current through a horizontal power line flows in east to west direction. What is the direction of magnetic field at a point directly below it and at a point directly above it?
25. List the properties of magnetic lines of force.
26. Why don’t two magnetic lines of force intersect each other?
27. Choose the correct option.The magnetic field inside a long straight solenoid-carrying current
a. is zero.
b. decreases as we move towards its end.
c. increases as we move towards its end.
d. is the same at all points.
28. State Fleming’s left-hand rule.
29. What is the role of the split ring in an electric motor?
30. Explain different ways to induce current in a coil.
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