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 (ii) withdrawn from inside the coil ?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.
16. A torch bulb is rated 2.5 V and 750 mA. Calculate (i) its power, (ii) its resistance and (iii) the energy consumed if this bulb is lighted for four hours.
17. Series arrangements are not used for domestic circuits. List any three reasons
18. A positively charged particle projected towards west is deflected towards north by a magnetic field. What is the direction of the magnetic field ? State the rule applied to determine direction of magnetic field
19. Explain why two magnetic lines do not intersect each other. State the rule for determining the direction of the magnetic field produced around a current carrying conductor. Draw a sketch of the pattern of field lines due to a current flowing through a straight conductor
20. (i) What is a solenoid ? Draw a sketch of the pattern of field lines of the magnetic field through and around a current carrying solenoid. (ii) Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right hand rule to find out the direction of the magnetic field inside and outside the loop.
21.(a) What is tidal energy ? (b) What is commercial unit of energy ?
22. What are renewable sources of energy? Give two example.
23. How many 40 W bulbs can be safely connected in a parallel circuit which is drawing current through a 5A fuse from a 220 V supply ?
24. How does the strength of the Magnetic field at the centre of a circular coil of a wire depend on : (a) radius of the coil (b) number of turns in the coil
25. Calculate the resistance of a conductor when the current flowing through it is 0.2 A and the potential difference is 0.8 V ?
26. (a) What is the function of an earth wire ? Why is it necessary to earth metallic appliances?
(b) What is the difference between overloading and short circuiting?