(Important Questions) Important Question For CBSE Class X Science Board Examination 2009-10 (Set -3)

Q. 1. A charge of 400 C flows through a conductor for 1.3 minutes and 20 seconds. Finds the magnitude of the current flowing through the conductor. [ 0.5 A]

Q. 2. A charge of 5000 C flows through an electric circuit in 2 hour and 30 minutes. Calculate the magnitude of the current flowing through the circuit. [0.555 A]

Q. 3. A dry cell can supply a charge of 300 C. If the current is drawn from the cell is 60 mA, find the time in which the cell completely discharges. 

Q. 4. A battery con supply a charge of 2.5 10⁵ C. If the current is drawn from the battery at a rate of 12.5 A, calculate the time in which the battery will be discharge. [20000 s]

Q. 5. A dry cell can supply a charge of 800 c. If a continuous current of 8.0 mA is drawn, calculate the time in which cell will be discharged completely. [100,000 s]

Q. 6. A charge of 25 mA flows for 2 hour through a conductor. Calculate the number of electrons, which drift in the conductor. [Charge on one electron = 1.6 x 10 ^{– 19} C]. [1.125 x 10 ²¹]

Q. 7. Calculate the total number of electrons flowing through a circuit in 20 minutes and 40 seconds, if a current of 40 mA flows through the circuit. [Charge on one electron = 1.6 x 10 ^-19 C]. 

Q. 8. 2.4 x 10 20 electrons flow through a circuit in 10 hours. Calculate the magnitude of the current. [Charge on one electron = 1.6 x 10^–19 C]. [1.066 x 10 ^{– 3} ]

Q. 9. 50 coulombs of charge is brought from infinity to a given point in an electric field when 62.5 j of work is done. What is the potential at that point? [1.25 V]

Q. 10. What is the electric potential at a point in an electric field when 24 j of work is done in moving a charge of 84 C from infinity?[0.285 V]

Q. 11. A charge of 75 C is brought from infinity to a given point in an electric field; when the amount of work done is 12.5 j. Calculate the electric potential at that point. [0.166 V]

Q. 12. A charge of 2 C is moved in and electric field from infinity to two points A and B. If the work done in bringing the charge to point A is 12j and in bringing it to point B is 16 j. Calculate the potential difference between points A and B. [2 V]

Q. 13. Word of 25j and 30j is dome when 5 C charge is moved from infinity to a point A and then to a point B respectively. Calculate the potential difference between the points A and B. [1 V]

Q. 14. A charge of 25 C is moved from infinity to two points A and B in and electric field. The work done to do so up to A and B is 10 j and 12.5 j respectively. What is the potential difference between points A and B? [0.1 V]

Q. 15. The resistance of a wire of length 80 cm and of uniform area of cross-section 0.025 cm²,is found to be 1.50ohm. Calculate sp. Resistance of wire. [0.000469 ohm. cm.]

Q. 16. A wire of resistance 4.5ohm and length 150 cm, has area of cross-section of 0.04cm². Calculate sp. Resistance of wire. [0.0012 ohm. cm]

Q. 17. What should be the length of nichrome wire of resistance 4.5 ohm, if the length of similar wire is 60 cm and resistance 2.5 ohm? [108 cm]

Q. 18. Resistance of a conductor of length 75 cm is 3.25 ohm. Calculate the length of a similar conductor, whose resistance is 16.25 ohm. [375 cm]

Q. 19. A nichrome wires has a resistance of 5 ohm. Find the resistance of another nichrome wire, Whose length is four times and area of cross-section three times the first wire. [6.6 ohm]

Q. 20. A resistance wire made from German silver has a resistance of 4.25 ohm. Calculate the resistance of another wire, made from same material. Such that its length increases by three times. [51 ohm]

Q. 21. A nichrome wire of length l and area of cross-section A/4 has a resistance R. Another nichrome wire of length 3l and area of cross-section A/2 has resistance of R₁. Find the ratio of R₁ and R. [3 : 2]