CURRENT ELECTRICITY

1. Kirchhoff's junction rule is a reflection of

• Conservation of current density vector

• Conservation of charge and no accumulation of charge at the the junction

• the momentum with which a charged particle approaches a junction is unchanged as the charged particle leaves the junction

• Conservation of energy

Which of the following characteristics of electrons determines the current in a conductor?

• Drift velocity alone

• Thermal velocity alone

• Both A and B

• Neither A nor B

By what percent the specific resistance of a conductor change when it is length is increased by two times.

• 10%

• 20%

• 5%

• No change

What is the potential difference across the combination of cells. The n number of identical cells ε are charged by ε'

• (εr + ε'R)/(R+nr)

• (R+nr)/(εr + ε'R)

• (εR + ε'r)/(R+nr)

• (εR + εr)/(R+nr)

A current of 5 Amp is allowed to flow through a wire of cross sectional area 5 mm². What will be the current density if the area vector describes an angle of 90⁰ to the electric current

• 2 x 10^-5 Am^-2

• 2 x 10^-6 Am^-2

• 5 x 10^-5 Am^-2

• 0

The conductance of a conductor of resistance 2 milli ohm

• 5 Siemen

• 0.5 Siemen

• 50 Siemen

• 500 Siemen

------ is called the increase in resistance per unit original resistance per degree kelvin rise of temperature

• Thermal velocity

• temperature coefficient of electrical resistivity

• temperature coefficient of electrical resistance

• conducance

72 cells of internal resistance 5 Ohm and emf 2.0 volt are used to send current through an external circuit of resistance 10 Ohm. What is the maximum current in the circuit

• 6/35 amp

• 12/35 Amp

• 24/35 Amp

• 35/24 Amp

When an electric field is applied across the ends of a conductor the electrons experience this..

• gains kinetic energy due to electric field

• loses kinetic energy due to electric field

• loses / gains kinetic energy during the collision in the direction of electric field

• loses/gains kinetic energy during the collision in the direction opposite to the direction of electric field

The average relaxation time during collision of electrons with atoms is

• 10^-14 sec

• 10^-10

• 10⁴

• 10¹⁴