The resistance of a conductor of diameter d and length l is R Ω. If the diameter of the conductor is halved and its length is doubled, the resistance will be

Related Mcqs:

1. Two copper conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductor will be_____________?

   A. 160 ohms
   B. 80 ohms
   C. 20 ohms
   D. 10 ohms

2. If a wire conductor of 0.2 ohm resistance is doubled in length, its resistance becomes______________?

   A. 0.4 ohm
   B. 0.6 ohm
   C. 0.8 ohm
   D. 1.0 ohm

3. Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes__________?

   A. 1/9 times
   B. 3 times
   C. 9 times
   D. unchanged

4. The resistance of a copper wire 200 m long is 21 Q. If its thickness (diameter) is 0.44 mm, its specific resistance is around_______________?

   A. 1.2 x 10~8 Q-m
   B. 1.4 x 10~8 Q-m
   C. 1.6 x 10″”8 Q-m
   D. 1.8 x 10″8 Q-m

5. An electric current induced within the body of a conductor when that conductor either moves through a non uniform magnetic field or in a region where there is a change in magnetic flux is called_____________?

   A. Induced current
   B. Eddy current
   C. Back emf
   D. None of the above

6. The resistance of a parallel circuit consisting of two branches is 12 ohms. If the resistance of one branch is 18 ohms, what is the resistance of the other ?

   A. 18 Q
   B. 36 Q
   C. 48 Q
   D. 64 Q

7. Four wires of same material, the same cross-sectional area and the same length when connected in parallel give a resistance of 25 Q. If the same four wires are connected is series the effective resistance will be________?

   A. 100 Ω
   B. 200 Ω
   C. 300 Ω
   D. 400 Ω

8. The resistance of a conductor varies inversely as___________?

   A. length
   B. area of cross-section
   C. temperature
   D. resistivity

9. The resistance of a few meters of wire conductor in closed electrical circuit is____________?

   A. practically zero
   B. low
   C. high
   D. very high

10. The hot resistance of the bulb’s filament is higher than its cold resistance because the temperature co-efficient of the filament is___________________?

    A. zero
    B. negative
    C. positive
    D. about 2 ohms per degree