1. Bio gas is also known as gobar gas. Justify.
2. Name the instrument used to measure electric current in a circuit.
3. The charge possessed by an electron is 1.6x10-19 coulombs. Find the number of electrons that will flow per second to constitute a current of 1 ampere.
4. What are permanent magnets and electromagnets ? Give one use of each.
5. Explain the role of fuse in series with any electrical appliance in an electric circuit ? Why should a fuse with defined rating for an electric circuit not be replaced by one with a larger rating
6. (a) Charcoal is a better fuel than wood. Why ? (b) How does biogas plant help to reduce the problem of pollution ?
7. Name the physical quantity which is (i) same (ii) different in all the bulbs when three bulbs of
(a) same wattage are connected in series (b) same wattage are connected in parallel
(c) different wattage are connected in series (d) different wattage are connected in parallel
8. Two devices of rating 44W; 220 V and 11W; 220 V are connected in series. The combination is connected across a 440 V mains. The fuse of which of the two devices is likely to burn when switch is on ? Justify your answer.
9. A coil made of insulated copper wire is connected to a galvanometer. What will happen to the deflection of the galvanometer if this coil is moved towards a stationary bar magnet and then moved away from it? Give reason for your answer and name the phenomenon involved.
10. (a) Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in coil B? Give reason. (b) State the rule to determine the direction of a : (i) magnetic field produced around a straight conductor carrying current. (ii) force experienced by a current carrying straight conductor placed in a magnetic field, which is perpendicular to it.
11. (a) A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is : (i) pushed into the coil with its north pole entering first ? (ii) withdrawn from inside the coil ? (iii) held stationary inside the coil ?
(b) Name the above phenomenon and mention the name of the scientist who discovered it. State the law that relates the direction of current in the coil with the direction of motion of the magnet.
12. (a) With the help of a labelled diagram, explain the distribution of magnetic field due to
a current through a circular loop.
(b) What is a solenoid ?
(c) Draw the pattern of magnetic field formed around a current carrying solenoid. Compare this field to that of a bar magnet.
13. An electric heater draws a current of 10A when connected to a 200 V supply. What current will the heater draw when it is connected to 220 V supply.
14. Insulation cover of which colour is conventionally used for earth wire ? Why is an earth wire connected to metallic parts of appliances ?
15. A 9W resistance is cut into three equal parts and connected in parallel. Find the equivalent resistance of the combination.
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