Current electricity- AFL

Potential difference between the terminals of a cell in an open circuit is,

• potential difference

• Terminal potential difference

• emf

How does resistivity depend on relaxation time ?

• directly

• inversely

• directly by its 4^th power

Which of the following equations is incorrect ?

• j =σ E

• j = i / A

• j= n e V_d

• j = e ζ /m

The relation between relaxation time and temperature can be expressed as;

• ζ ∝ temperature

• ζ ∝ 1/ temperature

• ζ is independent of temperature

For a) metals and b) semiconductors, the number of charge carriers

• a) remains constant b)increases

• a) increases b) increases

• a) decreases b) remains constant

• a) increases b) increases

The conductivity of a semiconductor ------- rapidly with temperature

• increases

• decreases

The dimensional formula of current density is

• ⌈ L^-2 A ⌉

• ⌈ L² A^-1⌉

• ⌊ L^-1 A² ⌋

Mobility is the ......

• ratio of electric field to the drift velocity

• product of drift velocity and relaxation tme

• ratio of drift velocity to the electric field.

If the current flowing in an iron wire is allowed to flow through another iron wire of double the radius,then what will be the effect on the drift velocity of the electrons ?

• would become double

• would become ¼

• would become ½

• no effect

n e V_{d = ____ ?}

• σ

• ρ

• j

• G