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CBSE Questions for Class 10 Physics Electricity Quiz 3 - MCQExams.com
CBSE
Class 10 Physics
Electricity
Quiz 3
A substance that allows electricity to pass through it, is called ______
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electrical conductor
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electrical insulator
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electrical semiconductor
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None of these
Explanation
Electrical conductors have free electrons in there outermost shell giving them the property of movement of electrons within the conductor structure and that movement of electrons is also called as current Hence, Electrical conductors provides easy passage to the electrons. Hence A option is correct
State whether given statement is True or False.
Silver is a good conductor of electricity.
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True
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False
Explanation
Silver, being a metal, is a good conductor of electricity. It is because the particles of silver provide a smooth path for electricity to pass through it with minimum difficulty.
Human nails are good insulators
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True
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False
Explanation
Human nails are good insulators. This statement is true because our nails are made up of a special type of cells known as keratin that are non-conductors of electricity.
________are substances which do not allow electricity to pass through them.
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Insulators
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Conductors
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Semi-conductors
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None of these
Explanation
The substance which do not allow electricity to pass through them are called $$insulators$$.
Answer-(A)
Find odd man out
Plastic, Rubber, Glass, Silver
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Glass
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Rubber
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Silver
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Plastic
Explanation
All are bad conductors (insulator) of electricity, but silver is a good conductor.
For a heater rated at $$4.4 \ kW \ , \ 220 \ V$$ . Calculate the current drawn by the heater.
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$$40 \ A$$
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$$20\ A$$
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$$12.6 \ A$$
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$$0 \ A$$
Explanation
Given:
$$V =220$$ volts
$$P = 4.4 \ kW = 4400 \ W$$
Since, $$ P = VI$$
Current drawn by heater $$I =\dfrac{P}{V} = \dfrac{4400}{220} = 20 \ A$$
For a heater rated at $$4 \ kW$$; $$220 \ V$$ . Calculate the resistance of the heater element.
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$$20 \Omega$$
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$$21.6\Omega$$
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$$200\Omega$$
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$$12.2\Omega$$
Explanation
Given: $$V =220$$ volts $$P = 4000$$ W
Electric power is given by
$$P=\dfrac{V^2}{R}$$ where $$R$$ is resistance and $$V$$ is voltage.
$$\therefore$$ Resistance of the heater $$R = \dfrac{V^2}{P} =\dfrac{220^2}{4000} = 12.1\Omega$$
For a heater rated at 4.4 KW; 220 V, calculate the energy consumed by the heater in 4 hours?
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12 KWh
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17.6 KWh
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0 KWh
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4.4 KWh
Explanation
Given : $$P = 4.4$$ KW, $$t = 4$$ h
$$\therefore$$ Energy consumed in 4 h
$$\Rightarrow E= P\times t =4.4\times 4 = 17.6$$ kWh
Mark the correct reason why a fuse is always connected in series
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When fuse melts, it breaks down the entire home circuit and no current flows
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In series connection the current for the entire house pass through the fuse
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Both
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None
Explanation
A fuse is always connected in series because
when fuse melts, it breaks down the entire home circuit and no current flows
$$\rightarrow$$ In series connection the current for the entire house pass through the fuse
Motion of charges is nothing but:
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electric current
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magnetic effect of current
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heating effect of current
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all of the above
Explanation
Movement of charges is called current. The current always flow in the opposite direction of the movement of electrons.
The rate of flow of electric charges is known as:
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Electric potential
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Electric conductance
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Electric current
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None of these
Explanation
Electric current is defined as the rate of flow of electric charges.
Current $$I = \dfrac{q}{t}$$ $$A$$, where $$q$$ is the amount of charge that flows in time $$t$$.
The SI unit of electric current is:
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Ohm
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Ampere
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Volt
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Faraday
Explanation
Electric current is defined as the rate of flow of electric charges.
Current $$I = \dfrac{q}{t}$$
The electric current is expressed by a unit called ampere (A), named after the French scientist,
Andre-Marie Ampere.
The source of electricity in a flash torch is its bulb.
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True
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False
Explanation
So, it is the cell or battery that acts as a source of electricity and not a bulb. Bulb glows when electricity is passed through it. Hence this statement is false. Bulb does not conduct electricity
An electric bulb is rated $$750 \ W - 200 \ V$$. Calculate the magnitude of current.
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$$200 \ A$$
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$$3.75 \ A$$
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$$15 \ A$$
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$$2 \ A$$
Explanation
Given, voltage $$V = 200 \ V$$ , Power $$ P = 750 \ W$$.
Using , $$P = Vi$$
$$i = \dfrac{P}{V} = \dfrac{750}{200} = 3.75 \ A$$
Hence, $$i = 3.75 \ A$$.
Heating effect of current is due to
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the flow of voltage through the conductor.
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the flow of current through a conductor.
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both A and B.
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neither A nor B.
Explanation
Whenever an electric current passes through a conductor, it gets heated up. The amount of heat produced is directly proportional to the square of the current ($$H\propto i^2$$).
When a current flows through a conductor its temperature
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May increase or decrease
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Remains same
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Decreases
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Increases
Explanation
According to Joule's heating effect of current, heat energy is generated across a conductor due to the current flowing through it and hence its temperature increases.
Calculate the current through a lamp of 25w operating at 220v.
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2A
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25A
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0.114A
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6A
Explanation
Given : $$P = 25$$ W $$V= 220$$ volts
$$\therefore$$ Current through the lamp $$I = \dfrac{P}{V} = \dfrac{25}{220} = 0.114$$ A
The direction of current is taken as
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The opposite to the direction of flow of current.
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Opposite to the direction of flow of protons.
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Opposite to the direction of flow of electrons.
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All
Explanation
Conventionally, the direction of current is taken as the direction of flow of positive charge (protons) and opposite to the direction of flow of negative charge (electrons).
Hence option C is correct.
When resistances are connected in series
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Same voltage is applied across all resistors
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Resistances must be same
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Same current flows through all resistances
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All
Explanation
The electrical components are said to be connected in series if physically same amount of current flows through them whereas potential difference gets divided according to the resistance across each component . Thus same current flows through all resistances which are connected in series.
This is because the current entering the one end of the series combination must leave its other end entirely because the combination doesn't store any charge.
i.e. $$I_{entering}=I_{leaving}$$
An electric stove uses _________ resistances.
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High
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Low
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Medium
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None
Explanation
According to Joule’s law of heating,
heat produced in a resistor $$(H)$$ is
(i) directly proportional to the square of current $$(I)$$
for a given resistance
(ii) directly proportional to
resistance $$(R)$$ for a given current, and
(iii) directly
proportional to the time $$(t)$$ for which the current flows
through the resistor
$$H=I^2Rt$$
An electric stove uses high resistance.
A bulb uses 5000J of energy in 10s, calculate its power.
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50 $$J/s$$
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500 $$Watts$$
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5 $$Watts$$
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600 $$J/s$$
Explanation
Given : $$E = 5000$$ J $$t = 10$$ s
Power of the bulb $$Power=\dfrac{Energy \quad spent}{Time}$$ $$P = \dfrac{E}{t} = \dfrac{5000}{10} = 500$$ $$Watts$$
SI unit of electrical energy is
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Joule
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Kilowatt hour
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KiloJoule
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Watt hour
Explanation
SI unit of electrical energy is Joule.
$$1 Joule = 1 Volt \times 1 ampere \times 1 second$$
An electric bulb works on the principle of:
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Archimedes
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Heating effect of current
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Magnetic effect of current
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None of these
Explanation
An electric bulb works on the principle of hearing effect of current. It consists of a tungsten filament with a coating of thorium. This filament gets heated up to emit light when current passes through it.
What is the series equivalent of $$1000 \ \Omega$$ resistor and $$2700 \ \Omega$$ resistor in series?
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$$2700 \ \Omega$$
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$$3000 \ \Omega$$
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$$3700 \ \Omega$$
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$$1000 \ \Omega$$
Explanation
Given : $$R_1 = 1000\Omega$$
$$R_2 = 2700\Omega$$
Equivalent resistance in series combination is given by
$$R_{eq} = R_1+R_2 = 1000+2700 = 3700$$ $$\Omega$$
What is the total resistance when four resistors of $$20, 40, 60$$, and $$80$$ respectively are connected in parallel (in ohm)?
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$$4.4$$
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$$9.6$$
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$$14.8$$
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$$20$$
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$$25.2$$
Explanation
Given : $$R_1 =20\Omega$$
$$R_2 =40\Omega$$
$$R_3 =60\Omega$$
$$R_4 =80\Omega$$
Equivalent resistance for parallel combination $$\dfrac{1}{R_{eq}} = \dfrac{1}{R_1} +\dfrac{1}{R_2}+\dfrac{1}{R_3}+\dfrac{1}{R_4}$$
$$\therefore$$
$$\dfrac{1}{R_{eq}} = \dfrac{1}{20} +\dfrac{1}{40}+\dfrac{1}{60}+\dfrac{1}{80}$$ $$\implies R_{eq} =9.6\Omega$$
Identify the changes in a circuit on adding a light bulb in parallel to the actual resistance of the circuit. It will:
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Decrease the total resistance
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Increase the total resistance
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Make the voltage lost in each light bulb different
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Make the current through each light bulb the same
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Not change the total current through the circuit
Explanation
For the parallel combination of two resistances
$$\dfrac{1}{R_{eq}} =\dfrac{1}{R_1} +\dfrac{1}{R_2}$$
$$\Rightarrow R_{eq}< min {R_1, R_2}$$
Light bulb has its own resistance and hence the total resistance of the circuit decreases when it is connected in parallel to the actual resistance of the circuit.
A $$10\ k\Omega$$ resistor can be obtained by using
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$$3\ k\Omega,5\ k\Omega,2\ k\Omega$$ resistors in series
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$$3\ k\Omega,5\ k\Omega,2\ k\Omega$$ Resistors in parallel
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$$3\ k\Omega,5\ k\Omega$$ in series and combination in parallel to $$2\ k\Omega$$ resistor in series
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$$5\ k\Omega,5\ k\Omega,2\ k\Omega,$$ Resistors in series
Explanation
When three resistors are connected in series, the equivalent resistance is
$$R_{eq}=R_1+R_2+R_3$$.
In the question, $$R_1=3\ k\Omega$$,
$$R_2=5\ k\Omega$$,
$$R_3=2\ k\Omega$$.
$$\therefore R_{eq}=3+5+2 = 10\ k\Omega$$
Current in circuit, which makes bulb glow or heats up the wire, is:
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motion of charges
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motion of atoms
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motion of molecules
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none of the above
Explanation
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor .It is often defined as rate of flow of charges.
Hence motion of charges through a conductor causes electric current.
The amount of charges that pass any section of the conductors in one second is called:
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Current
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Power dissipation
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Electromotive force
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Internal resistance
Explanation
Current is defined as the amount of charges that passes any section of the conductors in one second.
$$i = \dfrac{Q}{t}$$
$$Q$$; the amount of charges passing through cross section area
Identify the changes in a circuit on adding a light bulb to a series circuit. It will:
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increase the total resistance
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make the current through each light bulb different
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decrease the total resistance
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change the voltage of the battery
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make the voltage lost in each light bulb equal
Explanation
For series combination of two resistances $$R_{eq} = R_1 + R_2$$
Light bulb has its own resistance and thus the total resistance of the circuit increases when it is connected in series with the circuit.
What is the equivalent resistance of three $$1000 \ \Omega$$ resistors in series?
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$$1000 \ \Omega$$
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$$3000 \ \Omega$$
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$$2000 \ \Omega$$
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$$1100 \ \Omega$$
Explanation
Given : $$3$$ resistors of resistance $$R = 1000 \ \Omega$$
Equivalent resistance in series combinationis given by,
$$R_{eq} = R_1+R_2+R_3$$
$$R_{eq} = R+R+R = 3R = 3000 \ \Omega$$
What is the power produced by an appliance marked "240 V, 2 A"?
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8.3 mW
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60 W
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120 W
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480 W
Explanation
$$V=240 , I=2A$$
Power, $$P=V\times I=240\times 2=480W$$
Which of the following is an insulator?
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Wood
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Iron
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Carbon
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Silver
Explanation
Insulator is unable to transfer heat or electricity. Here the wood one of example of insulator because it is unable to transfer any heat or electricity.
Conventional
current is the direction of electric current from positive terminal of a cell to negative terminal.
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True
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False
Explanation
Conventional Current assumes that current flows out of the positive terminal, through the circuit and into the negative terminal of the source. This was the convention chosen during the discovery of electricity.
Electron Flow is what actually happens and electrons flow out of the negative terminal, through the circuit and into the positive terminal of the source.
Both Conventional Current and Electron Flow are used.
Electricity is a form of ____________
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Force
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Energy
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Tension
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Shock
Explanation
Electricity is a form of
energy
which is generated with quick movement of electron inside the atoms.
Option B
Insulators
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conduct electricity.
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do not conduct electricity.
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conduct electricity only at low temperatures.
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conduct electricity at room temperature.
Explanation
$$\textbf{Explanation}$$
$$\bullet$$Insulators doesn’t have free electrons , so current doesn’t flow through them.
$$\bullet$$ Hence they are not able to transfer electricity untill very high temperature is applied. Thus, insulators do not conduct electricity.
$$\textbf{ Hence option B correct}$$
Your are given three equal resistances. In how many combinations can they be arranged?
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Three
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Four
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Five
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Two
Explanation
Three equal resistances can be connected in four different combinations:
1) All three in parallel.
2) Two in parallel and third in series.
3) Two in series and third in parallel of both.
4) All three in series.
Which of the following component is connected in parallel in the circuit?
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Rheostat
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Capacitor
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Bulb
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LED
Explanation
Since the current in both bulbs is not same but they have same potential so they are connected in parallel.
Therefore, C is correct statement.
The equivalent resistance due to series connection of $$10\ \Omega$$ and $$10\ \Omega$$ resistors is
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$$5\ \Omega$$
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$$10\ \Omega$$
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$$0\ \Omega$$
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$$20\ \Omega$$
Explanation
For series connection(Current remains same):
$$R_{ (total)} = R_1 + R_2$$
In series combination equivalent resistance is total sum of the resistances.
$$\Rightarrow R_{total}=10+10$$
$$\Rightarrow R_{total}=20\Omega $$
If three resistors 2 ohm, 3 ohm and 4 ohm are connected in series, then effective resistance in a circuit will be _______ ohm.
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9
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6
0%
1
0%
5
Explanation
$$R_{eq}=R_1 + R_2 + R_3$$
$$=2+3+4= 9 \Omega$$
State whether given statement is True or False
In conductors, the innermost electrons are free to move :
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True
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False
Explanation
False
Innermost electrons are not free to move because they are tightly held by the attractive force by the protons present in the nucleus of the element. Only outermost electrons are free to move in conductors.
Which of the following is not a correct statement with respect to the given circuit?
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Switch $$S$$ is closed
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Current is flowing in the circuit
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$$B$$ and $$C$$ are connected in series
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$$A$$ is connected in series to $$B$$ and $$C$$
Materials that allow electrons to flow through them are known as
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Insulator
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Conductors
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Electrolytes
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Bases
Explanation
Materials that allow electrons to flow through them are known as conductors. They consist of free electrons and hence allow the flow of charges through them.
State whether given statement is True or False
The total resistance of a series circuit is equal to the difference between the largest and smallest value resistors.
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True
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False
Explanation
A series circuit is a circuit in which resistors are arranged in a chain, so the current has only one path to take. The current is the same through each resistor. The total resistance of the circuit is found by simply adding up the resistance values of the individual resistors:
equivalent resistance of resistors in series : $$R_s = R_1 + R_2 + R_3 + ...$$
Series aiding
is a term sometimes used to describe voltage sources of the same polarity in series.
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True
0%
False
Explanation
Series aiding voltage sources are series connected sources with their polarities connected so that the plus terminal of one is connected to the negative terminal of the next allowing current to flow in the same direction.
If the equivalent resistance is to be increased, then the number of resistances should be connected in:
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Series
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Parallel
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Mixed arrangement
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None of the above
Explanation
Equivalent resistance is maximum and current flow is minimum when number of resistances are connected in series.$$R_{eq}= R_1 + R_2 + R_3$$ ; where $$R_1,R_2,R_3$$ are resistances.
Why is electrical wiring usually made from copper?
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Because copper is shiny.
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Because copper conducts electricity.
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Because copper is not magnetic
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none of these
Explanation
Materials that allow an electric current to pass through them are called
conductors. Copper is a good conductor of electricity. The electrical wiring usually made from copper b
ecause copper conducts electricity.
Which of the following is true:
The direction of electric current in a conducting wire is _______
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in the direction of negatively charged particles but opposite to the positively charged particles
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in the direction of motion of electrons
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opposite to the direction of motion of electrons
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in the direction opposite to the motion of positively charged particles
Explanation
The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction in which the positive test charges are pushed to. Thus, these negatively charged electrons move in the direction opposite to the direction of electric current.
What is the unit of electric charge in SI system?
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Coulomb
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Volt
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Watt
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Ampere
Explanation
In the SI system, the unit of electric charge is coulomb.
In any electric circuit, when the switch is on and the current is flowing through it why do the wire, switches, bulb or devices in the circuit become hot?
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Because of the heating effect of electric current
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Because of the magnetic effect of electric current
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Because of the luminous effect of electric current
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None of these
Explanation
This is because some of the electric energy is converted into heat energy, i.e., heating effect of electric current.
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