Current Electricity class XII

A Carbon Resistor is marked in colour bands of Red, Black,Orange,Silver.What is the resistance and tolerance value of the resistor ?

• 20 kilo ohm & +- 10%

• 18 kilo ohm & +-5%

• 25 kilo ohm & +- 10%

• 20 kilo ohm

Is current density a scalar or vector quantity ?

A cell of emf (E) and internal resistance (r) draws a current (I). Write a relation between terminal voltage (V) in terms of E,I,r. ?

Though we specify the direction of direct current by putting an arrow, why is it not considered a vector quantity ?

• Because current does not obey the laws of vector addition

• Because charge is Quantized

• Because conventional direction of current is only virtual

• Because current obeys Kirchhoff Laws

As the temperature of a conductor increases both it's Resistivity and Conductivity change.Will the ratio of its Resistivity and conductivity

• Increases

• Decreases

• Remain same

• None of these

When is the Wheatstone bridge is most sensitive ?

• When all the four resistances of the bridge are equal

• When the bridge is balanced

• When high amount of current is flowing through the bridge

• When a very low amount of current is flowing through the bridge

The unit of electric power is

• Volt

• Joule

• kWh

• Watt

Current carriers in Electrolyte are/is

• Free electrons

• Holes

• Electrons and holes both

• Positive and negative ions

What will be the new resistivity of a metallic wire if it's length becomes double

• Increases two times

• Becomes half

• Increases four times

• Remains same

SI unit of current density is ......