Science : Important question : Electricity and Magnetic effects


  1.  A apiece of wire of resistance R is cut into five equal parts These parts are then connected in parallel than equivalent resistance
  2. The electric bulb is rated 220v and 100 w when it is operated on 110 v  than the power consumed
  3.  The conducting wires of the same material and of equal length and equal diameter are first connected in series and then parallel  in the circuit across the same potential difference find the ratio between two equivalent resistances .
  4.  How is voltmeter connected in circuit ?
  5.   A copper wire of diameter 0.5mm  resistivity of 0.0000016 ohm -m  what should be the length of wire to make the resistance of 10 ohm . ? When a 12 volt battery is connected to the unknown resistance give the current of 2.5mA find the value of resistance.
  6.  If the battery of 9V is connected to  .2 ohm, .3 ohm , .4ohm, .5 ohm and 12 ohm resistance connected in series  find the current flowing through 12 ohm resistance?
  7. How many 176 ohm resistances are required  to maintain the current of 5A through 220V. There three resistances of 6 ohm each  how will you connect the resistance to give 9 ohm  or 4 ohm equivalent resistance. How many lamps to be connected of 40w,220 v such that5A current flows through it.
  8. How many bulbs of 220V and 10W be connected in parallel to 220V mains to produce the current of 5A.  A hot plate having the  2 resistance of24 ohm each  can be used separately, /series / parallel is connected 220 mains  find the current in all cases
  9.  Compare the power  in 2 ohm resistor each case a) 6V battery in series with 1 ohm , ohm resistors b) 4V battery in parallel with 12 ohm and 2ohm resistors
  10.  What is the current flowing through the circuit when two bulb of 100w 220v and 60 w 220v connected parallel. What is the energy consumed if 250 w TV  used fir 1 hr  and toasters of 120 w  used for 30minutes.
  11.  Give reasons a) tungsten is used for filament in bulb .b)  Electric iron ,bread toaster  has conductors of alloy c)  series arrangement of circuit is not used in domestic wiring d) relation of resistance and aera of cross-section of conductor e) copper /aluminum wires are used in electricity transmission. f) relation of power and potential difference. g) Electric bulb is filled with which inactive gases  h) fuse is connected in live wire
  12.  A charge of 15 coulomb flows in one minute find the current flowing . What is the cost @ Rs 3/unit when heater of 800w is operated for 6hrs/day for 3 days. Find the equivalent resistance when 10 ohm,15 ohm 5 ohm resistance are connected in parallel Draw the graph of ohm’s law and explain it.
  13.  Nichrome wire of length of l of radius r has resistance of 10 ohm how is resistance changes when length of wire is made double  or if radius is made  doubled.
  14. Three resistors 5 ohm, 10 ohm , 15 ohm is connected in series with the battery of 30v draw the circuit  with ammeter and voltmeter find the current passing in 1o ohm .
  15. The electric iron  rated 840 w -360 w if connected to 220v find the resistance in minimum and maximum conditions.
  16.  A bulb of200v ,100w  calculate the resistance of  bulb  if 5 such bulbs  are connected  for 4 hrs find the unit consumed and cost @rs 4/unit.  Calculate the aera of cross-section of wire of length 625mm ,resistance 4 ohm and resistivity of 0.00000048 ohm -meter.
  17.  An electric lamp is connected to 4 ohm resistance in series such that current flowing is.25 A through battery of 6 v.
  18.  Drive the expression of combination of resistance in series and parallel. Two lamps of 40 w 220v ,and 100w 220v connected in parallel  calculate the resistance, current and energy of circuit.
  19.  Two resistances of 10 ohm , 15 ohm is connected  with 12 v battery find the minimum and maximum current flowing indifferent conditions .
  20.  What is the difference between AC and DC circuit ,write their frequency.  and graph.
  21. .Write three important features of domestic electric supply lines  with reference voltage, wire colour , and combination of circuit , what is overloading and short-circuiting .


  1.  where is the magnetic field near a long straight wire ? What is the phenomenon of electromagnetic induction?
  2. Name device used  for producing  electric-current is  generator/motor/ galvanometer.
  3.  What is the main difference between AC  generator and DC generator.
  4.  What happens about the current at the time of short circuiting.  when does it take place. What are three sources of magnetic fields.?
  5. How does a solenoid behave like magnet? How the North and south pole is determined in it?
  6. Draw a label diagram of electric motor . Explain the principle of motor and it’s working  and uses .
  7. A coil of insulated copper wire is connected to galvanometer  what happens to when bar magnet is i) pushed into the coil ii) withdrawn from inside the coil  iii) remain stationary in coil
  8. State the rule by which the direction of magnetic field is determine i) The magnetic field produced around a straight current carrying conductor  ii)Force experienced by the current carrying  straight conductor placed in magnetic field which is perpendicular to it. iii) Current induced in coil due to rotation  in magnetic field.
  9. Two  circular coils A and B are placed close to each d  if the current in coil flows in A is changed will the be any effect on B.
  10. Explain the principles of generator  with it’s working and diagram
  11. What is the angle between current and magnetic field  for maximum current in straight current carrying conductor ? Explain Fleming right hand rule.
  12.  List the properties of magnetic lines of forces.
  13.  Draw magnetic field lines produced around a current carrying straight conductor passing through cardboard .How will the strength of magnetic field changes ,when the point where magnetic field is to be determined is moved away from the conductor. or when current flowing increases
  14.  State Maxwell right hand thumb rule  ? Magnetic field lines close to the axis of current carrying loop as we move away from the center of loop we observe the lines keep on diverging why it is so.
  15. Explain the  effect of magnetic field produced at point in a current carrying circular coil  when a)amount of current is increased b)distance form the coil increase c)increase the number of turns.
  16. Show that a current carrying conductor experiences the force when placed  in magnetic field.
  17.  Draw the magnetic field lines of bar magnet  why two l magnet lines do not intersect each other
  18. The two coils P and Q  are wounded over the same iron core  Coil p is connected to a battery and key and coil Q is connected to galvanometer  what happens) current in coil P started by closed by . ii) Current continues to flow in coil P iii) Current in coil P is stopped  give reasons

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