Tiêu đề 03. CURRENT ELECTRICITY.pdf ✅

#QID# 37913 (1.) Which of the following graph represents the variation of resistivity ( ) with temperature (T) for copper?[2020] (1) (2) (3) (4) #QID# 37914 (2.) The solids which have the negative temperature coefficient of resistance are:[2020] (1) insulators only (2) semiconductors only (3) insulators and semiconductors (4) metals #QID# 37915 (3.) The color code of a resistance is given below Yellow Violet Brown Gold The values of resistance and tolerance, respectively, are[2020]
(1) 47kΩ,10% (2) 4.7kΩ,5% (3) 470Ω,5% (4) 470kΩ,5% #QID# 37916 (4.) A charged particle having drift velocity of 4 1 7.5 10 m s − −  in an electric field of 10 3 10−  1 Vm− , has a mobility in 2 1 1 m V s − − of: [2020] (1) 6 2.5 10  (2) 6 2.5 10−  (3) 15 2.25 10−  (4) 15 2.25 10  #QID# 37917 (5.) A carbon resistor of (47 4.7 k  ) Ω is to be marked with rings of different colours for its identification. The colour code sequence will be[2018] (1) Violet-Yellow-Orange-Silver (2) Yellow-Violet-Orange-Silver (3) Green-Orange-Violet-Gold (4) Yellow-Green-Violet-Gold #QID# 37918 (6.) The resistance of a wire is ' R ' ohm. If it is melted and stretched to ' n ' times its original length, its new resistance will be :-[2017] (1) R n (2) 2 nR (3) 2 R n (4) nR #QID# 37919 (7.) Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is :[2015] (1) current (2) drift velocity (3) electric field (4) current density #QID# 37920 (8.) A wire of resistance 4Ω is stretched to twice its original length. The resistance of stretched wire would be[2013]
(1) 4Ω (2) 8Ω (3) 16Ω (4) 2Ω #QID# 37921 (9.) Two rods are joined end to end, as shown. Both have a cross-sectional area of 2 0.01 cm . Each is 1 meter long. One rod is of copper with a resistivity of 6 1.7 10 ohm −  -centimeter, the other is of iron with a resistivity of 5 10 ohm − centimeter. How much voltage is required to produce a current of 1 ampere in the rods?[NEET Kar2013] (1) 0.117 V (2) 0.00145 V (3) 0.0145 V (4) 6 1.7 10 V −  #QID# 37922 (10.) A wire of a certain material is stretched slowly by ten per cent. Its new resistance and specific resistance become respectively:[2008] (1) 1.2 times, 1.3 times (2) 1.21 times, same (3) both remain the same (4) 1.1 times, 1.1 times #QID# 37923 (11.) The electric resistance of a certain wire of iron is R . If its length and radius are both doubled, then [2004] (1) the resistance and the specific resistance, will both remain unchanged (2) the resistance will be doubled and the specific resistance will be halved (3) the resistance will be halved and the specific resistance will remain unchanged (4) the resistance will be halved and the specific resistance will bedoubled #QID# 37924 (12.) A 6 volt battery is connected to the terminals of the three metre long wire of uniform thickness and resistance of 100ohm . The difference of potential between two points on the wire separated by a distance of 50 cm will be [2004]
(1) 1.5 volt (2) 3volt (3) 3 volt (4) 1 volt #QID# 37925 (13.) The resistivity (specific resistance) of a copper wire[2002] (1) increases with increase in its temperature (2) decreases with increase in its cross-section (3) increases with increase in its length (4) increases with increase in itscross-section #QID# 37926 (14.) Si and Cu are cooled to a temperature of 300 K , then resistivity?[2001] (1) For Si increases and for Cu decreases (2) For Cu increases and for Si decreases (3) Decreases for both Si and Cu (4) Increases for both Si and Cu #QID# 37927 (15.) A wire has a resistance of 3.1Ω at 30 C and a resistance 4.5Ω at 100 C . The temperature coefficient of resistance of the wire[2001] (1) 1 0.008 C− (2) 1 0.0034 C− (3) 1 0.0025 C− (4) 1 0.0012 C− #QID# 37928 (16.) The resistance of a discharge tube is[1999] (1) zero (2) ohmic (3) non-ohmic (4) infinity #QID# 37929 (17.) There are three copper wires of length and cross sectional area ( ) 1 1 , , 2 , , ,2 2 2             L A L A L A . In which case is the resistance minimum? [1997] (1) It is the same in all three cases (2) Wire of cross-sectional area 2A (3) Wire of cross-sectional area A (4) Wire of cross-sectional area 1 A 2 #QID# 37930