The plates of a capacitor are charged to a potential difference of 100V and are then connected across a resistor. The p.d across the capacitor decays exponentially with time After 1 s the potential difference between the plates of the capacitor is 80 volt. What is the fraction of the stored energy which has been dissipated?
1/25
1/5
9/25
16/25
Unit of conductance can’t be expressed in ____.
mho
(ohm)-1
siemen
ohm m-1
Reciprocal of resistivity of a conductor is ____.
conductance
capacitance
conductivity
None of the above
With rises in temperature the resistance of germanium ____.
increases
decreases
remains the same
first increases and decreases
A suitable unit for expressing electric field strength is ____.
V/C
C/m2
Am
N/C
Effective resistance of a circuit containing resistances in parallel is ____.
equal to the sum of the individual resistances
smaller than any of the individual resistances
greater than any of the individual resistances
sometimes greater and sometimes smaller than the individual resistances
Electric potential is ____.
a scalar quantity
a vector quantity
neither scalar nor vector
sometimes scalar and sometimes vector
What is immaterial for an electric fuse wire?
Its specific resistance
Its radius
Its length
Current flowing through it
When there is an electric current through a conducting wire along its length then an electric field must exist ____.
inside the wire but normal to it
inside the wire but parallel to it
outside the wire but normal to it
outside the wire but parallel to it
In the Bohr’s model of hydrogen atom, the electron moves around the nucleus in a circular orbit of radius 5x 10-11 meters. If its time period is 1.2 x 10-16 s, then current associated with the electron motion is ____,
zero
1.6 x 10-19 A
0.17 A
1.07 X 10-3 A