Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

for jee and boards > PHYSICS VIVA > Flashcards

PHYSICS VIVA Flashcards

1
Q

state ohm’s law

A

ohm’s law states that the eletric current I flowing through a conductor is directlyproportional to the potential difference V across its end provideed the physical condition like temperature pressure and dimension of the conductor remains same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

give mathmatical form of ohm’s law

A

V=IR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are ohmic devices

A

devices which obey ohms law are called ohmic devices
ex-metals like Cu,Al,Ag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are non ohmic devices

A

devices which are do not obey ohm’s law are called non ohmic devices
ex- diodes,transistors,vaccume tubes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is effect of temperature on the resistance of a conductor

A

increases with increase in the temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

+how do u conclude that the conductor used in a conductor obeyed ohm’s law

A

it is done by 2 methods
- the ration of volt meter reading and the corresponding ammeter reading comes to constant
- a graph btw v and i comes to a staight line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the factors affecting the resistance

A

length area of crosssection nature of material and temperature of conductance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

define resistance

A

opposition offered by the material of wire to the flow of the current
R=I/V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

define the unit of resiistance

A

1 ohm=1v/1A
the si unit of resistance is ohm
1ohm is the resistance of a conductor carrying current of one apere when potential difference is mainrained across its ends

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the cause of the resistance

A

collision of drifting electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the function of a rheostat

A

it is a variable resistance resistance and is commnly used for adjusting the strength of eletric current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is conductance

A

the reciprocal of resistance is called conductance. denoted by G
G=1/R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what does the slope of V-I graph reprents

A

resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

define resistivity or specific resistance of the material of conductance

A

resistance of a conductor of unit length and unit cross sectional area
unit is ohm meter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

define eletrical conductivity

A

reciprocal of resistance
represented by the symbol sigma=1/ro

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is wheat stone bridge

A

it is the arrangement of the 4 resistors in quadrilateral form to find the unknown resistance of the 4th resistor by the other 3 resistors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is meter bridge

A

it is the practical form of wheatstone bridge
it is used to determice the reistance and resistivity of a alloy wire

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

whenis a wheatstone bridge is said to be balanced

A

when no current flows through the galvanometer and it giives zero deflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the condition for a wheatstone bridge to be balanced

A

p/q=r/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is balancing length

A

it is length of the bridge wire for which trhe deflection shows zero deflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is null point

A

it is a point on the wire, keeping jockey at which the galvanometer gives zero deflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how does resistiviity of the conductor vary with length and area of cross section of the conductor

A

it is independet of length and area of cross section of the conductor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

when are the resitors are said to be connected in series

A

when they are connected in series and coneected in end end to manner so that the current flow is same through out the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

when does the resistors are said to be connected in parallel combination

A

when they are connected in a common pointg so that the pd is same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
when 2 reisitors are connected in seires the equivalent resistance is
Rs=R1+R2
25
when 2 resistance is connected in paralle lwhat is the equivalent series
I/Rp=1/R1+1/R2 => 1/Rp=(R1+R2)/(R1R2)
25
what heppens to the equivalent reisitance when the resistors are connected in seires
equivalent resistance will be than greater resistance
26
what happens to the equivalent resistoer when connected in parallel
equivalent resistance will be lesser than the least resistance
27
what is internal resistance of a cell
the opposition offered by the cell itself to flow the current
28
what is the internal resistance of an ideal cell
zero
29
what are the factors on which the internal resistance of a cell depends
1. distance btw the electordes 2. facing surface area 3.nature of electrode 4.internal resistance of the cell
30
does internal resistance of the cell depends on the external resistance connected
no
31
what is galvanometer
device used to detect feeble eletric current in the circuits
32
why divisions of a galvanometer scale are equally spread
the deflection of a needle is directly proportional to the current IαΘ
32
define figure of merit of a galvanometer
the quantity oof current required to produce a deflection of one division in the galvanometer is callled figure of merit of the galvanometer represented by k
33
define current sensivity
the deflection produced in the galvanometer when 1 unit of current is passed through it
34
what do u mean by resistance of a galvanometer
the resistance of the coil of a galvanometer denoted by G
34
why is this method called half deflection method
cause the deflection is made half by the shumt resistor
35
what is there zener diode
PN junction diode
36
mention any one applicaton of zener diode
voltage regulator
37
zener breakdown voltage
the voltage becomes constant and current increases
38
what iis voltage regulator
it is a device which produce a constant output voltaGE irrsepective of variation in the voltage
39
what is zener current
the reverse current after breakdown
40
what is voltmeter
a device measured for measuring eletric potential difference btw 2 points in a circuit
41
required properties for a volt meter
must have a large resistance and less current carrying capacity
42
why should a voltmeter have a very large resistance
when connected in parallel in circuit iit should not divert much current from parallel branch
43
why is galvanometer not suitable to work asvoltmeter
galvanomter has less resistance and more current carrying capacity is required
44
how is a galvanomter converted into a voltmeter
by connecting a high resistance in series with the galvanometer coil
45
how the high resistance in series gives required properties to the galvanometer
increases the overall resistance og the voltmeter and decreases its current carrying capacity
46
what is shunt ?its Si unit
small resistance connected in a parralel with the galvanometer Si unit is ohm
47
how is voltmeter to be connected in a circuit
connected in parallel with the circuit element across which the pd to measured
48
what is a resistance of a ideal voltmetr
infinite ∞
49
what is AC
current changes every instant of time and direction changes periodically
50
what is the unit of frequency of AC
hertz Hz per second
51
what is resonance
when the natural frequency of a partical is equal to the frequency of driving force then resonance takes place
52
when will wire resonate
the frequency of AC source is equal to the natural frequency of the vibration of the wire
53
what is resonating length
the distance btw 2 knife edges when resonance takes place
54
what iisan electromagnet
device which gets magnet when current is passed through it
55
how is the frequency of electromagnet related with the frequency of the alternating current which magnetise it
it is twice the frequecny of AC
56
what is natural frequency of the sonometer wire
f=1/2L(√T/µ) where, µ= linear mass density T= tension in the wire L=length of the wire
57
what are stationary waves
when 2 identical waves moving in same frequency and amplitude ina medium with the same speed but in opposite direction
58
what are nodes and antinodes
nodes are point of zero amplitude and antinodes are points of maximum amplitude
59
define a spherical lens
a piece of transparent medim bounded by at least one spherical surface
60
describe different types of lenses
(i)convex lens and (ii)concave lens (i) thick in middle and thin in outside (ii)thin in middle and thick in outside
61
define apertus of a lens
the diameter of the circular edge of the lens is called the aperture of the lens
62
define optical centre of a lens
it is a fixed poinmt inside the lens on its principal axis through which the light passes undeviated
63
what is the type of a eye lens
eye lens is convex
64
can u find the focal length of a concave lens by distant object method
no because it does not form a real image to be obtained on a screen
65
what is the focal length of a lens
distance btw optical centre and the principal focus of a lens Si unit is meter
66
what are the practical use of lens
spectacles,microscope,telescope,other optical uses
67
define SI unit of power
diopter is SI unit of power one diopter is the power of lens whose focal length is one mete
67
what are the sign for the power of a convex lens and concave lens
concave lens- +ve and focal lengthis +ve convex lens- -ve and focal length is -ve
68
on what factors do focal length of convex lens depends
- radii of curvature of lens - refractive index of lens - refractive index of surrounding medium -wavelength of light used
69
what is lens maker formula
it is the relkation btw focal length and radii of curvature refractive index ofthe material of lens and refractive index of surroundings

for jee and boards (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions