CURRENT ELECTRICITY

Question 1

The motion of free electrons inside conductor is

Answer 1

random motion

Question 2

what is drift velocity?

Answer 2

the uniform velocity gained by free electrons of conductor when it is attached with the battery of certain voltages

Question 3

the value of random velocity of electrons is

Answer 3

10^+5 m/s

Question 4

the value of drift velocity is

Answer 4

10^-5 m/s

Question 5

the angle between drift velocity and electric intensity is

Answer 5

180°

Question 6

the formula for drift velocity is

Answer 6

Vd = △V/neρL
OR
Vd = I/neA

Question 6

what is electric current?

Answer 6

the rate of flow of charge to any cross-section of wire

Question 6

formula for current

Answer 6

I = △Q/△t
OR
I = ne/△t

Question 7

unit for current

Answer 7

ampere = coulomb / second

Question 8

how many electrons per second constitute a current of 1 ampere?

Answer 8

6.25 x 10^18 e

Question 8

state ohms law

Answer 8

current flowing through a conductor is directly proportional to the potential difference applied across its ends, provided that the physical state of the conductor remains same

Question 9

the proportionality constant for ohm’s law is

Answer 9

1/R

Question 10

write formula for ohm’s law

Answer 10

I = 1/R x V
V= IR

Question 11

formula for resistance

Answer 11

R = V/ I

Question 12

unit for resistance

Answer 12

ohm = volt / ampere

Question 13

resistance depends upon

Answer 13

resistivity (ρ)
temperature
nature
length
area

Question 14

base units of ohm are

Answer 14

kg m2 / sec3 A2

Question 15

the slope for VI graph gives

Answer 15

R

Question 16

the area under VI graph gives

Answer 16

Pave
average power

Question 17

the graph between V and I is

Answer 17

straight line originating from origin

Question 18

for a graph of VI where 4 lines are originating from axis, where a is closer to x-axis and d is closer to y-axis, what is the decreasing order of resistances?

Answer 18

Rd > Rc > Rb > Ra

Question 19

a graph is drawn between V at x-axis and I at y-axis. four straight lines are originating from origin, with line ‘a’ being close to x-axis and line d being close to y-axis, what is the decreasing order of resistances?

Answer 19

Ra > Rb > Rc > Rd

Question 20

a VI graph is drawn, with straight lines A and B originating from origin. line A is at 30° with x-axis and line B is at 30° from y-axis. what is the ratio of resistance of A to B?

Answer 20

3 : 1

Question 21

for series combination of resistances, what is Req?

Answer 21

Req = R1 + R2 + R3

Question 22

for series combination of resistors, which is same: current or voltage?

Answer 22

current

Question 23

for series combination of resistors, the Req is _________ that any individual resistances.

Answer 23

greater

Question 24

what will be Req for series combination of resistors, if all resistances are same?

Answer 24

Req = nR

Question 25

for parallel combination of resistor, the equivalent resistance will be

Answer 25

1/Req = 1/R1 + 1/R2 + 1/R3

Question 26

for parallel combination of resistors, which is same, current or voltage?

Answer 26

voltage

Question 27

the equivalent resistance for parallel combination of resistors is __________ than any individual resistance.

Answer 27

smaller

Question 28

the equivalent resistance for parallel combination of resistors if all the resistances are equal is

Answer 28

Req = R/n

Question 29

formulas for power

Answer 29

P = W/t OR P = VI OR P = I^2 R (for series) OR P = V^2/R (for parallel)

Question 29

what is the manufacturing formula for bulb?

Answer 29

P = V^2/R

Question 30

power is _________ proportional to area of filament

Answer 30

directly

Question 30

what is power?

Answer 30

the rate of dissipation of electrical energy

Question 31

the resistance of a bulb is _______ proportional to its power

Answer 31

inversely

Question 32

1 unit of electricity is equal to how many kWh

Answer 32

1

Question 32

power is ________ proportional to the brightness for series circuit

Answer 32

inversely

Question 32

the bulb with highest power has ______ filament

Answer 32

thickest

Question 33

power is _____ proportional to brightness for parallel circuit

Answer 33

directly

Question 34

define electromotive force.

Answer 34

the work done on unit positive charge by the cell or battery is called electromotive force.

Question 35

the terminal voltage is always ______ than emf

Answer 35

less

Question 36

formula for emf if work and charge is given would be

Answer 36

emf = W/Q

Question 36

the SI unit for emf is

Answer 36

volt

Question 37

emf if terminal voltage, current and resistance is given would be

Answer 37

emf = V + Ir

Question 38

formula for emf for closed circuit would be

Answer 38

emf = V + Ir

Question 38

emf for open circuit is

Answer 38

V (terminal voltage)

Question 39

formula for emf of charging circuit would be

Answer 39

emf = V - Ir

Question 40

emf for short circuit would be

Answer 40

Ir

Question 41

emf for closed circuit will be _______ than terminal voltage

Answer 41

greater

Question 42

emf for open circuit will be ______ than terminal voltage

Answer 42

less

Question 43

Power output formula is

Answer 43

e^2 R / (R - r)^2 + 4rR

Question 44

maximum power output will be

Answer 44

e^2/4r

Question 45

Kirchhoff's first rule can also be written as

Answer 45

sum of currents flowing towards a point is equal to the sum of currents flowing away from that point

Question 45

state Kirchhoff's first rule

Answer 45

sum of all currents flowing in a closed loop is equal to 0

Question 46

mathematical representation of Kirchhoff's first rule

Answer 46

Σ I = 0

Question 47

Kirchhoff's first rule is another form of

Answer 47

law of conservation of energy

Question 48

state Kirchhoff's 2nd rule

Answer 48

sum of all potential changes in a closed loop is always equal to 0

Question 48

Kirchhoff's first rule is also known as

Answer 48

current rule, point rule or junction rule

Question 49

mathematical form of Kirchhoff's 2nd rule

Answer 49

Σ V = 0

Question 50

Kirchhoff's 2nd rule can also be written as

Answer 50

energy gained is equal to energy lost

Question 51

Kirchhoff's 2nd rule is also known as

Answer 51

voltage rule or loop rule

Question 51

Kirchhoff's 2nd rule is another form of

Answer 51

law of conservation of energy

Question 52

resistance is ______ proportional to length

Answer 52

directly

Question 53

resistance is ___________ proportional to area

Answer 53

inversely

Question 54

proportionality constant for R ∝ l/A is

Answer 54

ρ

Question 55

ρ is called

Answer 55

resistivity of conductor

Question 56

ρ depends on

Answer 56

nature of conductor and temperature of conductor

Question 57

what is affected by bending, compressing, stretching and cutting; resistance of resistivity?

Answer 57

resistance

Question 58

shortcut to find resistance of a conductor if it is stretched will be

Answer 58

n^2 R

Question 59

shortcut to find resistance of conductor if it stretched will be

Answer 59

R / n^2

Question 60

write 3 formula for resistance

Answer 60

R = ρ L/A OR R = 4ρL/ π D^2 OR R = ρL/π r^2

Question 60

the reciprocal of resistance is called

Answer 60

conductance

Question 60

formula for conductance is

Answer 60

1/R

Question 61

unit of conductance is

Answer 61

mho, 1/ohm,

Question 62

the reciprocal of resistivity will be

Answer 62

conductivity

Question 63

formula for temperature coefficient would be

Answer 63

α = Rt - Rnot / Rnot △T

Question 64

α is positive for

Answer 64

conductors

Question 65

α is negative for

Answer 65

semi-conductors