Physics

Front 1

Difference between Ohmic and Non ohmic resistor

Back 1

1) Obeys the ohm law - Doesn't obey

V/I is constant - V/I is different for different values of V and I

2)The VI graph is a straight line through origin - curved line ,not necessary to pass through origin.

3)slope of V/I graph is same at given temp - not same at given temo

Front 2

Factors that affect Resistance of a conductor

Back 2

1)Nature of Conductor

2)Length ( directly proportional)

3)Thickness (indirectly proportional)

4) Temp (direct)

Front 3

What is resistivity

Back 3

Front 4

What affects specific resistance

Back 4

1)Different for different substances

2) Temp ( direct) but indirect for semi conductors

Front 5

What is a fuse wire made out of

Back 5

Lead and tin

Front 6

Filament of bulb ( non ohmic)

Back 6

Tungsten

Front 7

What is a superconductor

Back 7

A superconductor is a substance of zero resistance of infinite conductance at a very low temperature example Mark III below 4.2 K and let below 7.25 K , and niobium below 9.2 k

Front 8

Factors affecting emf

Back 8

The EMF of a cell depends on

1) the material of the electrodes

2) the electrolyte used in cell

Front 9

Factors affecting internal resistance

Back 9

1) surface area of electrodes(indirect

2) distance between the electrodes( direct)

3) the nature and concentration of electrolyte ( direct(

4) temperature of the electrolyte (indirect)

Front 10

Heating effect of current

Back 10

1) amount of current passing through the wire (direct to the square of current )

2) resistance of the wire (direct)

3) time for which current is passed (direct)

Front 11

Advantage of ring system

Back 11

1)no need of direct connection to mains for every appliance hence saves money

2)Each appliance can work independently even if other have got fused

3)when installing new appliance no new lineup required but only a connection from the ring is required

Front 12

Disadvantage of connecting in serioes

Back 12

1)voltage gets divided into appliances

2)Resistance increases hence decreasing the current so each appliance gets less power

3)no appliance can be operated independently

Front 13

Rise in temperature of fuse wire depends on?

Back 13

1) current rating

2) it's radius

Front 14

Similarities between solenoid and bar magnet

Back 14

Front 15

Dissimilarities between current carrying solenoid and bar magnet ?

Back 15

1)strength of magnetic field can be changed by increasing current while magnetic field of bar magnet is fixed

2)direction of magnet can be reversed by reversing the direction of current

Front 16

How to increase magnetic field of an electro magnet

Back 16

1)increasing no. Of turns in the solenoid

2)increasing the current

Front 17

Electro magnet Vs Permanent Magnet

Back 17

Front 18

Advantages of electromagnet over permanent magnet

Back 18

1) can produce a strong magnetic field

2) strength of magnetic field can easily be changed

3)Polarity can be reversed

Front 19

Convention for circuits ( old Nd new)

Back 19

Front 20

How to increase speed of rotation of DC motor

Back 20

1) increasing strength of current in the coil, coil means the shaft where the current pass thru that is ABCD

2)Increasing no. Of turns in the coil

3) increasing area of coil

4) by increasing strength of magnetic field

Front 21

What effect the induced emf

Back 21

1) rate of change of magnetic flux with each turn

2) no. Of turns in coil

Front 22

Turns ration

Back 22

Ns/Np

Front 23

Es/EP= Turns ration

Back 23

Es= EP*turns ratio

Front 24

Turns tattoo and all formula

Back 24

Front 25

Step up Vs step down

Back 25

Front 26

Condition to hear an echo

Back 26

1)distance between source and reflector must be 17 m

2) size of reflector must be large enough to compared to the wavelength of the sound

3) the intensity of sound should be such that after reflection it can be heard

Front 27

Why ultrasonic waves are used

Back 27

1)they can travel undeviated thru a long distance

2)They can be confined to a narrow beam

3)they are not easily absorbed into a medium

Front 28

SONAR AND RADAR

Back 28

Sound navigation and ranging

Radio detection and ranging

Front 29

Uses of echo

Back 29

1)imaging of organs - ultrasonography

2) echo cardiography

phy

Front 30

Electron volt

Back 30

The energy of atomic particles is measured in eV

eV is the energy gained by an electron when it is accelerated through a PD of 1 volt ,

1eV = 1.6*10^-19

Front 31

Calorie

Back 31

1 calorie is the heat energy required to raise temp of water at 14.5°C to 15.5°C

1J = 0.24calorie

Front 32

Relation of momentum with K.E.

Back 32

Momentum = p

p = mv

mv

Front 33

What does work energy theorem say

Back 33

The work done by a force on a moving body is equal to the increase in its kinetic energy

W= Kf-Ki