Which of the following materials has the least resistivity ?
Mercury
Lead
Zinc
Copper
Copper
When current flows through heater coil it glows but supply wiring does not glow because
current through supply line flows at slower speed
supply wiring is covered with insulation layer
resistance of heater coil is more than the supply wires
supply wires are made of superior material
resistance of heater coil is more than the supply wires
The condition for the validity under Ohm’s law is that
resistance must be uniform
temperature at positive end should be more than the temperature at negative end
resistance must be wire wound type
current should be proportional to the size of the resistance
resistance must be uniform
Which of the following statement is correct ?
A semi-conductor is a material whose conductivity is same as between that of a conductor and an insulator
A semi-conductor is one which con¬ducts only half of the applied voltage
A semi-conductor is a material which has conductivity having average value of conductivity of metal and insulator
A semi-conductor is a material made of alternate layers of conducting material and insulator
A semi-conductor is a material whose conductivity is same as between that of a conductor and an insulator
A rheostat differs from potentiometer in the respect that it
offers large number of tapping
has higher wattage rating
has lower wattage rating
has large number of turns
has higher wattage rating
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
1.6 x 10″”8 Q-m
1.2 x 10~8 Q-m
1.4 x 10~8 Q-m
1.8 x 10″8 Q-m
1.6 x 10″”8 Q-m
An instrument which detects electric current is known as
wattmeter
rheostat
voltmeter
galvanometer
galvanometer
Four wires of same material the same cross-sectional area and the same length when connected in parallel give a resistance of 0.25 Q. If the same four wires are connected is series the effective resistance will be
1 Q
2 Q
4 Q
3 Q
4 Q
A current of 16 amperes divides between two branches in parallel of resistances 8 ohms and 12 ohms respectively. The current in each branch is
6.4 A 9.6 A
4.6 A 9.6 A
4.6 A 6.9 A
6.4 A 6.9 A
6.4 A 9.6 A
Current velocity through a copper conductor is
of the order of a few ^.s/m
independent of current strength
the same as propagation velocity of electric energy
nearly 3 x 108 m/s
of the order of a few ^.s/m
पोस्ट अच्छी लगी हो तो प्लीज नीचे दिए गए लिंक पर क्लिक कर शेयर जरुर करें
0 Comments