Conduct electricity only at low temperatures

Conduct electricity at room temperature

MCQ Questions for Class 12 Medical Physics Current Electricity Quiz 2

Constantan wire is used for making standard resistance, because it has

0%
high melting point.
0%
low specific resistance.
0%
high specific resistance.
0%
negligible temperature coefficient of resistance.

A dynamo develops

$0.5 A$ at

$6 V$ . The energy which is generated in one second is

0%
$0.083 J$
0%
$3 J$
0%
$12 J$
0%
none of these

Explanation

Given:

Voltage(V) =

$6V$

Current(I) =

$0.5A$

Time(t) =

$1sec$

Energy generated =

$VIt$

$\Rightarrow$ Energy

$= 6\times 0.5 \times 1=3 J$

Copper metal is a:

0%
good conductor of electricity
0%
bad conductor of electricity
0%
magnetic substance
0%
bad conductor of heat
0%
none of these

Name the instrument used to control the current in an electric circuit.

0%
Rheostat
0%
Voltmeter
0%
Ammeter
0%
Galvanometer

1 kilowatt hour

$=$ ___________ .

0%
$10.6 \times 10^6$ Joule
0%
$3.6 \times 10^6$ Joule
0%
$30.6 \times 10^6$ Joule
0%
$3.6 \times 10^5$ Joule

Explanation

$1\ watt = 3600\ joule$

$1\ kW = 1000\ watt$

$1\ h=60\times 60 = 3600\ s$

$1\ kWh= 1\ kW\times 1\ hour=1000\ W\times 3600\ s = 1000 \times 3600 joule = 3.6 \times 10^{6}\ J$

The common dry cell produces a voltage of:

0%
$1.5 V$
0%
$30 V$
0%
$60 V$
0%
$3 V$

Explanation

A common dry cell is a type of electricity producing chemical cell , commonly used today for many home and portable devices, often in form of batteries.

By standards, a common dry cell has a constant voltage of

$1.5V$ .Hence correct option is A.

Insulators:

0%
Conduct electricity
0%
Do not conduct electricity
0%
Conduct electricity only at low temperatures
0%
Conduct electricity at room temperature

Explanation

$\textbf{Correct option: Option (B).}$

$\textbf{Explanation:}$

Insulators have tightly bound electrons which cannot move freely and hence cannot conduct electricity.

$\textbf{Thus, option (B) is correct.}$

Which is/are the insulators ?

0%
wax
0%
silver
0%
ebonite
0%
gold

The insulator of electricity is :

0%
copper
0%
silk
0%
human body
0%
acidulated water

A material that lets electricity to pass through it is called a/an:

0%
electrical conductor
0%
electrical insulator
0%
electrical appliance
0%
key

Fill in the blank.
Connecting wires in a electric circuit are made of .......

0%
copper
0%
silicon
0%
tin
0%
lead

Which of the follwing does not belong to the group formed by the others?

0%
Iron
0%
Tin
0%
Glass
0%
Steel

A cell is used to :

0%
measure current in a circuit.
0%
provide current in a circuit.
0%
check current in a circuit.
0%
prevent current in a circuit.

A material that does not allow electricity to flow through it is called a/an:

0%
Electrical conductor
0%
Electrical insulator
0%
Electrical appliance
0%
Key

If the resistance of a circuit is halved and the potential difference is kept constant, then the current will become

0%
4 times
0%
8 times
0%
double
0%
half

Explanation

Answer is C.

According to Ohm's law, V = IR. That is, I = V/R.
Now, if the resistance is halved and the voltage remains the same, the new value of current becomes,

$I'=\dfrac { V }{ \dfrac { R }{ 2 } } =\dfrac { 2V }{ R } .\quad That\quad is,\quad I'=2(\dfrac { V }{ R } )=2I$ .
Hence, the current will become double.

One Volt is equal to -

0%
1 Joule
0%
1 Newton/Coulomb
0%
1 Joule/Coulomb
0%
1 Coulomb/Newton

Explanation

$\bullet$ Volt is the electrical unit of voltage or potential difference

$(V)$ .

$\bullet$

$V$ is related to Change in Potential Energy

$\Delta U$ as

$V = \cfrac{\Delta U}{q}$

From above formula, We get

$1$ Volt potential difference when a change of

$1$ joule of Potential energy is there in moving a charge of

$1$ Coulomb.

Therefore,

$1$ Volt =

$1$ Joule/Coulomb.

A current of 300 mA is made to flow through a 6k

$\Omega$ resistor. What is the potential difference across the resistor?

0%
1800V
0%
50V
0%
0.02V
0%
500V

Explanation

Answer is A.

According to Ohm's law, V = IR.
Here, I = 300 mA = 0.3 A and R = 6000 ohms.
Therefore,

$V = 0.3\times 6000 = 1800 V.$
Hence, the p.d. across the resistor is 1800 V.

An electrical appliance has a resistance of 4 ohms. When it is connected to a 12 V battery, the number of coulombs passing through it per second is

0%
1.2
0%
12
0%
0.3
0%
3

Explanation

Answer is D.

The coulomb is defined in terms of the ampere and second:

$1 C = 1 A \times 1 s$ .
In this case, the resistance

$4$ ohms and voltage

$V = 12 V.$

According to Ohm's law,

$V = IR$

That is,

$I = \dfrac{V}{R}$

So,

$I = \dfrac{12}{4} = 3 A$

Hence, 3 coulomb of charge flows through the electrical appliance in 1 second.

Consider a circuit which contains a resistance free battery and a single resistance

$R$ . If a second resistance is added in parallel with

$R$ .

0%
The voltage across $R$ will decrease
0%
The current through $R$ will increase
0%
The total current drawn from the battery will increases
0%
The power dissipated in $R$ will decrease current drawn from battery will increase

Explanation

From given question, A new resistance has been adding to the older resistance circuit. Because this connection is making in parallel so potential difference will be same in each resistors which is equal to initial value. Both resistance will draw equal current that is equal to

$V/R$ and equal power that is equal to

$V^2/R$ but total current from the battery will be sum of currents in individual resistance that is equal to

$2V/R$ . Hence The total current drawn from the battery will increases.

Hence Option C

State True or False :

The materials, which do not allow electric current to pass through them easily, are poor conductors of electricity.

0%
True
0%
False

The potential difference across a

$6\Omega$ resistor is

$12V$ . The current flowing in the resistor will be

0%
4A
0%
2A
0%
0.5A
0%
1A

You are given three bulbs 25 W, 40 W and 60 W . Which of them has the lowest resistance?

0%
25 watt bulb
0%
40 watt bulb
0%
60 watt bulb
0%
Insufficient data

In 5s, a charge of 25C leaves a battery, and 100 J of energy are delivered to an outside circuit. What is the potential difference across the battery?

0%
20V
0%
125V
0%
4V
0%
8V

Explanation

Answer is C.

Here, the time taken t is 5 seconds, amount of charge q is 25 C and the work done w is 100 J.
We know that, the current I = Amount of charge/Time taken.
That is, I = q / t, 25/5 = 5 A.
Work done = Energy dissipated = Pt or

$VI\quad \times \quad t\quad as\quad P=VI$ .
Therefore,
W = V*I*t.
So, 100 = V*5*5.
V = 100/25 = 4 V.
Hence, the potential difference across the battery is 4 V.

An electric iron is rated at 3kw. Electrical energy costs Rs. 4 per kwh. What is the cost of using the iron for 5 hours?

0%
Rs.12
0%
Rs. 20
0%
Rs.150
0%
Rs. 60

Explanation

Answer is D.

Energy (

$power\times time$ ) is measured in Joules and by including time (t) in the power formulae, the energy dissipated by a component or circuit can be calculated.
Energy dissipated = Pt.
In this case, the power of the electric iron is rated as 3 kW and it runs for 5 hours.
Total power dissipated = 3 kW * 5 hrs = 15 kWh.
It is given that the cost of 1 kWh is Rs. 4.
Therefore, total cost = 15 kWh * 4 = Rs. 60.
Hence, the cost of using the iron for 5 hours is Rs. 60.

The unit of e.m.f. of a cell is:

0%
dyne
0%
volt
0%
ampere
0%
joule

Which among the following is measured in Kilowatt hour?

0%
Energy
0%
Power
0%
Resistance
0%
Current

Which one of the following substances are used to make electric switches and switch boards?

0%
Conductors
0%
Insulators
0%
Semiconductors
0%
None of the above

A substance that allows electricity to pass through it, is called ______

0%
electrical conductor
0%
electrical insulator
0%
electrical semiconductor
0%
None of these

Two resistors of 60 ohms and 40 ohms are arranged in series across a 220 volt supply. How much heat is produced by this combination in half a minute?

0%
12860J
0%
152698J
0%
650J
0%
14520J

Explanation

Answer is D.

Components connected in series are connected along a single path, so the same current flows through all of the components. 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. The total resistance of resistors in series is equal to the sum of their individual resistances. That is,

${ R }_{ total }={ R }_{ 1 }+{ R }_{ 2 }...{ R }_{ n }$ .
In this case, the total resistance is 60+40 = 100 ohms and the total voltage is 220 V.
Energy (

$power\times time$ ) is measured in Joules and by including time (t) in the power formulae, the energy dissipated by a component or circuit can be calculated.
Energy dissipated = Pt or

$VI\quad \times \quad t\quad as\quad P=VI$ .
It can also be written as

$P=\frac { { V }^{ 2 } }{ R } \times t\quad as\quad I=\frac { V }{ R }$ .
Here, V = 220 V, R = 100 ohms and t = half minute = 30 seconds.
Therefore,

$P=\frac { { 220 }^{ 2 } }{ 100 } \times 30=\quad 14520\quad J$ .
Hence, the heat produced by this combination in half a minute is 14520 J.

The maximum number of 40 W bulbs connected in parallel which can be lighted safely using a 240 V supply with a 5A fuse is.

0%
30
0%
45
0%
8
0%
44

Which among the following is the commercial unit of electrical energy?

0%
Volt
0%
Watt
0%
Ampere
0%
KWh

In 220 V A.C., the value of 220 represents:

0%
Normal voltage
0%
Effective voltage
0%
Constant voltage
0%
Peak voltage

The potential difference between the terminals of an electric heater is 220 V and the current is 5A. What is the resistance of the heater?

0%
22 ohm
0%
11 ohm
0%
44 ohm
0%
1100 ohm

How much electrical energy is transferred per second by a 4V; 0.5A lamp?

0%
20 J/S
0%
2 J/S
0%
6.8 J/S
0%
4.8 J/S

Explanation

Answer is B.

Energy (

$power\times time$ ) is measured in Joules and by including time (t) in the power formulae, the energy dissipated by a component or circuit can be calculated.
Energy dissipated = Pt or

$VI\quad \times \quad t\quad as\quad P=VI$ .
In this case, V = 4 V, I = 0.5 A and t = 1 second.
So, the electrical energy transferred is P = VI = 4 * 0.5 = 2 J/s.
Hence, the electrical energy is transferred per second by a 4 V and 0.5 A lamp is 2 J/s.

An electric cell does 5 joules of work in carrying 10-coulomb charge around the closed circuit. The electromotive force of the cell is :

0%
2 volt
0%
0.5 volt
0%
4 volt
0%
1 volt

A material that does not allow electricity to flow through it is called a/an-

0%
Electrical appliance
0%
Electrical conductor
0%
Electrical Insulator
0%
None of these

E.M.F. ofa cell is expressed in

0%
volt
0%
volt per metre
0%
volt metre
0%
none of these

Explanation

E.m.f of a cell is defined as the maximum potential difference across the cell when no current flows through the circuit.

Hence e.m.f is expressed in volt

$(V)$ .

State whether given statement is True or False
Glass is a good insulator.

0%
True
0%
False

Electric current can flow through-

0%
Silver
0%
Copper
0%
Iron
0%
All of these

The EMF of a cell can be defined as:

0%
Work done in taking a unit positive charge once round the circuit
0%
The open circuit voltage of the cell
0%
The terminal voltage when the current is zero
0%
All the above

Explanation

EMF of cell can be defined as:

$\rightarrow$ Workdone in taking unit positive charge once round the circuit

$\rightarrow$ The open circuit voltage of cell

$\rightarrow$ The terminal voltage when current is zero

A material that lets electricity to pass through it is called a/an-

0%
Electrical appliances
0%
Electrical conductor
0%
Electrical insulator
0%
None of these

Which of the following does not belong to the group formed by the others?

0%
Iron coin
0%
Wooden ruler
0%
Silver cup
0%
Copper wire

State whether given statement is True or False.
Silver is a good conductor of electricity.

0%
True
0%
False

What is the driving force in a working Electrical Circuit?

0%
Voltage Difference
0%
Current
0%
Temperature difference
0%
Chemical Imbalance

Find the odd man out.

Copper, Aluminium, Iron, Wood, Brass.

0%
Wood
0%
Aluminium
0%
Iron
0%
Brass

Find odd one out:

Copper, Salt water, Cotton, Human body.

0%
Human body
0%
Cotton
0%
Salt water
0%
Copper

A bulb uses 5000J of energy in 10s, calculate its power.

0%
50 $J/s$
0%
500 $Watts$
0%
5 $Watts$
0%
600 $J/s$

Explanation

Given :

$E = 5000$ J

$t = 10$ s

Power of the bulb

$Power=\dfrac{Energy \quad spent}{Time}$

$P = \dfrac{E}{t} = \dfrac{5000}{10} = 500$

$Watts$

Given a current carrying wire of non-uniform cross-section. Which one of the following is constant through out the length of wire ?

0%
Current only
0%
Current and drift speed
0%
Drift speed only
0%
Current, electric field and drift speed

________are substances which do not allow electricity to pass through them.

0%
Insulators
0%
Conductors
0%
Semi-conductors
0%
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

0%
Glass
0%
Rubber
0%
Silver
0%
Plastic

CBSE Questions for Class 12 Medical Physics Current Electricity Quiz 2 - MCQExams.com

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Practice Class 12 Medical Physics Quiz Questions and Answers

CBSE Questions for Class 12 Medical Physics Current Electricity Quiz 2 - MCQExams.com

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Practice Class 12 Medical Physics Quiz Questions and Answers

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