Current Electricity

Question 1

Resistivity depends on

Answer 1

Nature of material, temp, pres, independent of size & shape

Question 2

Drift Vel formula

Answer 2

V(d) = -eE(tou)/m, tou is avg time b/n 2 successive collisions

Question 3

If galvanometer & cell are exchanged at balance point, current?

Answer 3

0

Question 4

Under balanced condition, E1/E2 =

Answer 4

L1/L2

Question 5

Power transmission is done in very high voltage. Why?

Answer 5

P is inversely prop to V^2 so it reduces power loss

Question 6

temp coefficient of resistivity α for semiconductor, conductors & alloys

Answer 6

α is -ve of semiconductors
α is +ve for conductors & alloys

Question 7

alloys have ______ resisitivity than conductors

Answer 7

high

Question 8

When accelerating potential inceases, mobility

Answer 8

doesn’t change

Question 9

Limitations of Ohm’s law?

Answer 9

1. V/I ratio needn’t be unique for same value of I ie there could be more than 1 voltage for I.
2. V/I depends on sign of V. So reversing the dir of V doesn’t produce I of same magnitude.
3. V ceases to be prop to I

Question 10

V/I ratio may not be unique for

Answer 10

good conductors

Question 11

V/I depends on sign of V for

Answer 11

Gallium Arsenide

Question 12

V doesn’t produce I of same magnitude for

Answer 12

Diodes

Question 13

When does resistivity deviate for good conductors with current

Answer 13

When current increases

Question 14

τ dependence with ρ

Answer 14

inverse

Question 15

For _______, no. density of free e’s is almost independant of temp

Answer 15

Metals

Question 16

Resistivity of Nichrome has

Answer 16

weak temp dependence

Question 17

Resisitivity of manganin & constantan is

Answer 17

temp independent

Question 18

α is +ve & ρ is less for

Answer 18

metals

Question 19

diamond is an

Answer 19

insulator

Question 20

Graph of ρ with temp for metals

Answer 20

slowly increasing

Question 21

graph of ρ with Temp for alloys

Answer 21

increases starting not from origin but from a distance on the y-axis

Question 22

τ doesn’t change with temp for

Answer 22

insulators and semiconductors

Question 23

Examples of semiconductors

Answer 23

silicon & germanium

Question 24

graph of ρ with temp for semiconductors

Answer 24

inversely prop graph

Question 25

What is internal resistance

Answer 25

Resistance offered by the cell to flow of I through itself

Question 26

ε Vs R graph

Answer 26

Const from a dist on y-axis

Question 27

V Vs R graph

Answer 27

increasing and later reaching saturation point

Question 28

V Vs I graph

Answer 28

-ve slope ie -r

Question 29

Terminal pd when cell is charging

Answer 29

V = ε + Ir

Question 30

Junction rule/KCL

Answer 30

In a circuit, the sum of currents entering the junction is equal to sum of currents leaving the junction

Question 31

Loop Rule/KVL

Answer 31

The algebraic sum of EMFs in any loop is equal to sum of products of current & resistance

Question 32

KCL is based on ________ & KVL is based on

Answer 32

conservation of charge; conservation of energy