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Electricity 7&8 Flashcards

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1
Q

Dry cell eg

A

Voltaic cell , Daniel cell

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2
Q

SI unit of electrical resistance

A

Ohm

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3
Q

What is ammeter

A

An instrument used to measure current in amperes

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4
Q

From where does current actually move in an electric cell

A

From negative to positive

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5
Q

What is voltage

A

Difference in electrical potential energy,per unit of charge,btw two points.

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6
Q

Device used to identify charge of the object

A

Electroscope eg gold least electroscope

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7
Q

BOT -

A

1kWh

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8
Q

Secondary cells are also called

A

Storage cells or accumulators

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9
Q

What is galvanometer

A

Used to measure small electric current.

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10
Q

Microwave electrical energy

A

1500W

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11
Q

Eg of secondary cells

A

Lead accumulators.

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12
Q

What do you mean by a 9 volt battery

A

It means that there is a potential difference of 9 volt between the 2 terminals which charges to move with a specific energy of 9 joules.

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13
Q

Colour of neutral wire

A

Black or yellow or blue

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14
Q

Diff btw parallel and series circuit

A

Parallel- same voltage

Series- share volta

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15
Q

What is fuse

A

Is a wire made of tin and lead with a porcelain holder

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16
Q

Colour of earth wire

A

Green

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17
Q

Dry cell example

A

Modified Leclanche cell was discovered by Georges Leclanche

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18
Q

1 kWh =

A

1000Wh

=3.6 x 10 raised to 6 joules in one hour

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19
Q

1 coulomb is equal to the

A

Charge of many electrons( negative energy)that is 6.25 x 10 raised to 18

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20
Q

Electric iron

A

1000W

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21
Q

Induction

A

Charging the body by bringing a charged object closely to it

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22
Q

Explain the working of secondary cell

A

There are six cells in one secondary cells. Each cell has one negative and one positive terminal . The negative cell is lead while the positive terminal is lead oxide . Each cell has a strength of 2 volts. The secondary cell contains Sulphuric acid. The vessel is made of hard rubber,glass or celluloid.

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23
Q

SI unit of charge

A

Coulomb

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24
Q

Electrical resistance is directly proportional to the

A

Temperature

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25
Q

How can you measure the intensity of electric current called ampere

A

If a charge of Q coulombs flow through a conductor in t time then intensity of electric current measured in amperes represented by I isQ/T . 1 ampere is 1 coulomb of charge flowing at a certain point at 1 second .

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26
Q

BOT full form

A

Board Of Trade unit

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27
Q

If there is more voltage

A

More current would flow

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28
Q

Colour of live wire

A

Red

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29
Q

What do you mean by anode and cathode

A

Anode is the metal to be deposited and is attached to the positive terminal. Cathode is the metal on which it has to be deposited .

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30
Q

SI unit of electric current

A

Ampere(I)

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31
Q

Explain process of electroplating

A

The copper sulphate sol, when electricity passes through it splits into cu2 + and so2-.cu2+ is attracted towards the cathode attached to the negative cell . Where electrons are given out by the electric cell.The cu2+ molecules absorb the electrons given out by the cell. They become stable molecules. After that ,the cu in the anode donates electrons to the positive terminal to create a stable ion called cu2+ Which is then attracted towards the cathode and takes electrons from the negative terminal to form a stable ion called cu. thus during this process the cu (copper)gets deposited on the cathode and the content of the anode gets eroded

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32
Q

Bulbs in a house are connected in …………connection

A

Parallel

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33
Q

Voltage main function

A

To push electrons in a circuit

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34
Q

Electrical energy used by air conditioner

A

2000 to 3000 W

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35
Q

Electrolyte used in simple voltaic cell

A

Sulphuric acid

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36
Q

A charged body creates an

A

Electric field around it

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37
Q

What is the relationship between an electric field and an magnetic field

A

A moving electric field creates a magnetic field and vice versa

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38
Q

According to the relationship between electric and magnetic fields what happens when a charged body moves

A

A charged body always has an electric field around it and as it moves a magnetic field is also created

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39
Q

In a proton the electric field radically points

A

Outwards

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40
Q

In an electron the electric field radically points

A

Inwards

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41
Q

Magnetic effect of electric current first discovered by

A

Hans Christian oersted

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42
Q

Electrical power is

A

Electrical energy / time

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43
Q

Instrument that measures electrical power in watts

A

Wattmeter

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44
Q

Ohms law

A

Voltage=rate of flow of current x resistance

P= I x V

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45
Q

Joules law of heating

A

Heat energy liberated in a circuit is

H = I*2 . R . T(time for which current is flowing)

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46
Q

1 Kwh = how many joules

A

3.6 x 10*6

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47
Q

All ionic compounds are

A

strong electrolytes, because they mostly break up into ions as they dissolve in water.

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48
Q

Why do ionic compounds dissociate in water

A

if the energy given off when the ions interact with water molecules compensates for the energy needed to break the ionic bonds in the solid and the energy required to separate the water molecules so that the ions can be inserted into solution.

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49
Q

Resistance of a resistor increases with its

A

First , Resistivity of that substance

And also length increases-more distance the electrons have to bump

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50
Q

Resistance of a resistor is inversely proportional to

A

Area-as area increases the no of electrons flowing at a point through the resistor increases

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51
Q

Resistance offered by a resistor formula

A

R = p x length/ area (p - resistivity)

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52
Q

A example of a rechargeable battery

A

Ni - fe accumulator

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53
Q

1 horse power (hp) = ? Watts

A

746 watts

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54
Q

A charged body creates an

A

Electric field around it

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55
Q

What is the relationship between an electric field and an magnetic field

A

A moving electric field creates a magnetic field and vice versa

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56
Q

Magnetic effect of electric current first discovered by

A

Hans Christian oersted

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57
Q

Electrical power is

A

Electrical energy / time

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58
Q

Instrument that measures electrical power in watts

A

Wattmeter

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59
Q

Ohms law

A

Voltage=rate of flow of current x resistance

P= I x V

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60
Q

Joules law of heating

A

Heat energy liberated in a circuit is

H = I*2 . R . time for which current is flowing

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61
Q

1 Kwh = how many joules

A

3.6 x 10*6

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62
Q

Why do ionic compounds dissociate in water

A

if the energy given off when the ions interact with water molecules compensates for the energy needed to break the ionic bonds in the solid and the energy required to separate the water molecules so that the ions can be inserted into solution.

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63
Q

Diamagnetic objects ?

A

materials that are not affected by a magnetic field.

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64
Q

Paramagnetic objects

A

materials like aluminum or platinum which become magnetized in a magnetic field but their magnetism disappears when the field is removed.

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65
Q

Ferromagnetic objects

A

materials (such as iron and nickel) that can retain their magnetic properties when the magnetic field is removed.

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66
Q

Charge is a

A

Scalar quantity

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67
Q

Charge cannot exist without

A

Mass

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68
Q

Quantisation of charge

A

It means charge cannot have any arbitrary value but is defined as a integral multiple of the basic unit such as electron

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69
Q

Charge of one electron

A

1.6 x 10 raised to -19 C

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70
Q

Charge of an object (q) is

A

ne
e - charge of proton
n - any integer

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71
Q

Quantisation of charge was first suggested by

A

Michael faraday

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72
Q

Quantisation of charge experimentally demonstrated by

A

Millikan in 1912

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73
Q

Conservation of charge

A

Charge cannot be destroyed nor created

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74
Q

Charge is invariant

A

It means charge of an object always remains same , even if it is accelerated and until charge is removed from it.

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75
Q

3 methods of charging

A

Conduction
Friction
Induction

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76
Q

Which type of charging is most preferred

A

Induction because a charged body can be used to charge Maza y other objects without losing its charge

77
Q

Dielectric constant also called

A

Relative permittivity

78
Q

Dielectric constant denoted by

A

K

79
Q

Coulomb’s constant

A

K = 9 x 10 raised to 9 N m sq. C raised to -2

80
Q

Principle of superposition (electricity)

A

It states that when a number of charges are interacting with each other , the total force on a given charge is vector sum of forces exerted on it by all other charges

81
Q

Linear charge density

A

Charge per unit length

82
Q

Linear charge density is represented by

A

Lambda

83
Q

Surface charge density

A

Charge per unit area

84
Q

Electric field ?

A

A region surrounding a charge in which its electrical effects are perceptible.

85
Q

In an electric field , crowded lines represent

A

A stronger field

86
Q

Number of lines originating or terminating on a charge is proportional to its

A

Magnitude

87
Q

If a body has a charge of q , then no electric field lines (electrical flux) it has is

A

q / E°

E° - permittivity of free space

88
Q

E° is the value of

A

Permittivity of free space

89
Q

E° value?

A

8.854 x 10-12 C2 N-1 m-1

90
Q

Electric dipole

A

Pair of two equal and opposite charges separated by a small distance

91
Q

Point charges

A

Point particles with electric charge

92
Q

Inside a conductor electric field is

A

0

93
Q

3 types of capacitors

A

Parallel plate capacitors
Cylindrical capacitor
Spherical capacitor

94
Q

Capacitor function is to

A

Store Charge

95
Q

A capacitor consists of

A

2 metal strips separated by an insulating material called dielectric

96
Q

Every substance has a quality called

A

Dielectric constant - (K)

97
Q

Capacitance of a capacitor tells us

A

How much charge it can store

98
Q

Charge stored in the metal pieces are both

A

Equal and opposite

99
Q

Capacitors are usually charged by a battery and the voltage between the metal pieces is equal to

A

The voltage of battery

100
Q

Capacitance formula

A

C = Q/V

C - capacitance
Q - charge in one of the metal pieces
V - voltage between the metal pieces

101
Q

When a dielectric is introduced between 2 metal pieces in a capacitor

A

The molecules in it gets polarised

102
Q

Due to the polarisation of dielectric in a capacitor -

A

Voltage decreases.
C = Q/V
So capacitance increases

103
Q

If a battery is connected when the dielectric is placed between the metal pieces of the capacitor

A

The polarisation of dielectric reduces voltage between the metal pieces
But it is the battery’s responsibility to see that there is the same voltage in the entire circuit.
So it starts to accumulate more charge in both metal pieces to make the voltage stable,thus at this time, amount of charge in both metal pieces increases.
So according to the formula- C = Q/V - capacitance increases

104
Q

Unit of capacitance

A

Farads (F)

105
Q

How to calculate the change a dielectric will bring to the capacitance of capacitor

A

Every substance has something called dielectric constant (K).
So what you have to do is multiply the capacitance of the capacitor when it had no dielectric with the dielectric constant and that will be your new capacitance

106
Q

pF -

A

Picofarad = 10*-12 farad

107
Q

Capacitance is a

A

Scalar quantity

108
Q

Insulators also called

A

Dielectrics

109
Q

Electric constant

A

E° also termed as permittivity of free space.

The symbol is read as epsilon naught

110
Q

……………. has lowest electrical permittivity

A

Vacuum

111
Q

Dielectric constant (k) is

A

Electrical permittivity of that substance
Divided by
Electrical permittivity of vacuum

112
Q

Every substance has a dielectric constant more than

A

1

113
Q

Surface charge density represented by

A

Sigma

114
Q

Strength of electric field

A

2 x Coulomb’s constant x pi x surface density

115
Q

What is electrical potential energy

A

If a charge Q moves with a voltage V then the change in potential energy of that charge is Q times V .

116
Q

Potential energy stored in a capacitor ?

A

1/2 x Q(charge) x voltage

117
Q

In any circuit connection if you add the voltages of each of the capacitors it will be equal to

A

The voltage of the battery

118
Q

In a series connection capacitance is added by the formula

A

1/C = 1/C1 + 1/C2 + 1/C3 + ………..

119
Q

In a parallel connection capacitance is added by the formula

A

C = C1 + C2

120
Q

When two capacitors with different potentials are connected to each other then

A

Charge moves from the higher potential to the lower potential until the potential becomes equal. This equal potential is called common potential

121
Q

Common potential of two capacitors

A

Total charge / total capacity

122
Q

In a series connection ………… is same
In parallel connection ………… is same
( for capacitors )

A

Charge, voltage

123
Q

Capacitance of a spherical conductor of radius R

A

4 x pie x permittivity of free space x R

124
Q

Symbol for capacitor of variable capacitor has

A

an arrow

125
Q

Electric flux represented by the Greek symbol

A

Phi

126
Q

Electrical flux can be found by

A

Multiplying strength of the electric field E with area A of a surface perpendicular to the field

127
Q

To formulas for electrical flux

A 
Flux = electrical field x area = E x A
Flux = Q / E°

Q- charge enclosed
So flux = EA = Q / E°

128
Q

Capacitance directly proportional to

A

Area

129
Q

Maxwells equations contain how many equations

A

4

130
Q

Maxwells equation?

A

Gauss’ law
Gauss’ law for magnetism
Ampere’s law
Faraday’s law

131
Q

Gauss’ law for magnetism

A

This law states that magnetic monopoles do not exist

Every magnet is a dipole

132
Q

Faraday’s law states that

A

Any change to the magnetic environment of a coil of wire , would cause a voltage to be induced on the coil

133
Q

Ampere’ law states that

A

the magnetic field created by an electric current is proportional to the size of that electric current, with a constant of proportionality equal to the permeability of free space. .

134
Q

An infinitely uniformly charged plane produces a

A

Constant electric field

135
Q

Magnetic constant (mue 0)

A

4π × 10*−7 N/A2

136
Q

Electric charge is a

A

Fundamental property

137
Q

The discovery that amber rubbed by wool or silk attracted light objects was done by

A

Thales of Greece in 600 BC

138
Q

Name electricity coined from the

A

Greek word - elektron meaning amber.

139
Q

Property which differentiates the 2 kinds of charge

A

Polarisation of charge

140
Q

Names were given to the 2 kinds of charge by

A

Benjamin Franklin

141
Q

Who first observed that compass needle was deflected by a wire carrying electricity

A

Oersted , and supported by Michael faraday and Ampere.

142
Q

Who proposed the theory which unified electric current and magnetism

A

Maxwell and Lorentz

143
Q

An application which is connected in a circuit

A

Load (L)

144
Q

Deflection of the needle on galvanometer shows

A

Presence of current and direction of deflection indicates direction of current

145
Q

Ammeter is joined in

A

Series connection

146
Q

An ammeter has a

A

Low resistance

147
Q

In a series circuit, the current through each of the components is the same, and the voltage across the circuit is the sum of the voltages across each component. In a parallel circuit, the voltage across each of the components is the same, and the total current is the sum of the currents through each component.

A

Read

148
Q

Resistance wires usually made of a compound called

A

Manganin

149
Q

Rheostat

A

A device used to adjust the magnitude of current in a circuit by changing the length of resistance wire.

150
Q

Symbol used for variable resistance

A

Rh

151
Q

Voltmeter has high

A

Electrical resistance so that it does not draw out much current from the circuit

152
Q

Manganin composition

A

84% copper , 12% manganese , 4% nickel

153
Q

Lead accumulators also called

A

Acid accumulators

154
Q

Ni-Fe accumulators also called

A

Alkali accumulators

155
Q

Alternating current ?

A

A current whose both magnitude and direction change with time. The current repeats it’s value after a fixed time

156
Q

Voltage of current reaching in homes of India

A

230 Volts

157
Q

In an electric cell the positive electrode is called

A

Cathode

158
Q

Potential is a

A

Scalar quantity

159
Q

Potential SI unit is

A

Volt

160
Q

1 horsepower = how many watts

A

746

161
Q

Resistors in the higher range is usually made of

A

Carbon

162
Q

How quickly an electron can flow through a conductor

A

Electron mobility

163
Q

Drift velocity

A

Average speed that a particle like an electron attains in a material due to an electric field

164
Q

Drift velocity =

A

Electron mobility x strength of electric field

165
Q

1 kWh is equal to

A

3.6 x 10 raised to 6 joules

166
Q

Internal resistance of a cell represented by a

A

r

167
Q

Electromotive force represented by

A

A laterally inverted 3

168
Q

Kirchhoff’s first law also called

A

Kirchhoff’s junction law or Kirchhoff’s current law

169
Q

Kirchhoff’s first law states that

A

total current entering a junction is equal to the total current leaving the junction. OR The algebraic sum of currents at a junction is zero.

170
Q

Kirchhoff’s second law also called

A

Kirchhoff’s loop law or kirchhoff’s voltage law

171
Q

Meter bridge is a device used for

A

Measuring unknown resistance

172
Q

On rubbing substances with each other , those substances which are likely to get a positive charge

A

Fur , wool
Glass
Hair
Nylon or acetate

173
Q

On rubbing substances with each other , those substances which are likely to get a negative charge

A

Silk , ebonite , amber , rubber , plastic

174
Q

Eg of semiconductors

A

Silicon , Germanium

175
Q

Non electrolyte

A

A solution of a chemical compound which do not conduct electric current and hence do not undergo any chemical change

176
Q

Eg of non electrolytes

A

Petrol , kerosene oil , diesel , vegetable oil , chloroform , carbon tetrachloride , alcohol , ether , benzene , distilled water

177
Q

For making metals shiny it is usually electroplated with

A

Nickel and chromium

178
Q

Coulomb was named after the French physicist

A

Charles Augustin de Coulomb

179
Q

Triboelectric effect

A

a type of contact electrification on which certain materials become electrically charged after they come into frictional contact with a different material. Rubbing glass with fur, or a plastic comb through the hair, can build up triboelectricity.

180
Q

Coulomb’s constant

A

8.987551

181
Q

Electrostatic equilibrium definition

A

It is the position where the resultant force on a charged particle becomes 0.

182
Q

Electric charge definition (IJSO book)

A

It is the intrinsic property of certain fundamental particles like electron, quarks etc due to which they PRODUCE magnetic and electric effects.

183
Q

The charge of a macro body =

A

The excess or deficiency of electrons in the body.

184
Q

An algebraic expression becomes a polynomial only when -

A

All the coefficients are real numbers.

All the powers of the variables are positive integers.

185
Q

A polynomial whose coefficients are all zeros :

A

Zero polynomial.

186
Q

Degree of a zero polynomial is

A

Not defined.

187
Q

The real number “c” is a root of f(x) only if

A

f(c) = 0

188
Q

Proof of remainder theorem

A

p(x) = q(x) (x-a) + r

Let x = a
p(a) = q(a) x 0 + r
p(a) = r

Physics (17 decks)

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