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Physics MCQ

Electrical Power and Household Circuits · ICSE STD 10 (ICSE - English Medium). 43 questions.

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43 questions · timed · auto-graded

MCQ 11 Mark
A switch must be connected in :
  • ✓
    Live wire
  • B
    Neutral wire
  • C
    Earth wire
  • D
    Either earth or neutral wire
Answer
Correct option: A.
Live wire
A switch must be connected in live wire.
Explanation: A switch must be connected in live wire, so that when it is in 'off' position, the circuit is incomplete and no current reaches the appliance through the live wire.

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MCQ 21 Mark
The rating of a fuse connected in the lighting circuit is :
  • A
    15A
  • ✓
    5A
  • C
    10A
  • D
    Zero
Answer
Correct option: B.
5A
5 A

Hint: The electric wiring for light and fan circuit uses a thin fuse of low current rating (= 5 A) because the line wire has a current carrying capacity of 5 A.

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MCQ 31 Mark
The electric meter in a house records:
  • A
    Charge
  • B
    Current
  • ✓
    Energy
  • D
    Power
Answer
Correct option: C.
Energy
Energy

Hint: The electric meter in a house records the amount of electrical energy consumed in a house.

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MCQ 41 Mark
The electrical appliances in a house are connected in:
  • A
    Series
  • ✓
    Parallel
  • C
    Either in series or parallel
  • D
    Both in series and parallel
Answer
Correct option: B.
Parallel
Electrical appliances in a house are connected in parallel.Hint: On connecting the electrical appliances in parallel, each appliance works independently without being affected whether the other appliance is switched on or off.
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MCQ 51 Mark
The main fuse is connected in :
  • ✓
    Live wire
  • B
    Neutral wire
  • C
    Both the live and earth wires
  • D
    Both earth and the neutral wire
Answer
Correct option: A.
Live wire
The main fuse is connected in live wire.

Hint: The main fuse is connected in live wire so that if the current exceeds its rating, the fuse melts and breaks the circuit; thus, preventing the excessive current from flowing into the circuit.

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MCQ 61 Mark
Identify the option that displays the correct wiring with correct colour code:
  • A
    Image
  • B
    Image
  • ✓
    Image
  • D
    Image
Answer
Correct option: C.
Image
(c)
Live: Brown Neutral: blue Earth: Yellow
Explanation:
According to the new international convention, the colour for live wire is brown, for neutral wire is light blue and for earth wire is green or yellow.
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MCQ 71 Mark
The electrical meter in a house measures the:
  • A
    Charge
  • B
    Current
  • ✓
    Energy
  • D
    Power
Answer
Correct option: C.
Energy
(c)
Energy
Explanation:
The electrical meter tracks the consumption of energy, measured in kilowatt-hours, reflecting the total power used over time..
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MCQ 81 Mark
Electrical appliances in a house are typically connected:
  • A
    In series
  • ✓
    In parallel
  • C
    Either in series or parallel
  • D
    Both in series and parallel
Answer
Correct option: B.
In parallel
(b)
Parallel
Explanation:
Appliances are connected in parallel to ensure each one receives the full voltage required for proper operation, and they operate independently of each other.
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MCQ 91 Mark
The main fuse should be connected in the:
  • ✓
    Live wire
  • B
    Neutral wire
  • C
    Both the live and earth wires
  • D
    Both the earth and neutral wires
Answer
Correct option: A.
Live wire
(a)
Live wire
Explanation:
The main fuse is connected to the live wire to ensure that any current exceeding its capacity causes the fuse to blow, breaking the circuit and preventing potential damage.
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MCQ 101 Mark
The main switch in a household electrical system is typically a
  • A
    Single pole switch
  • B
    Triple pole switch
  • ✓
    Double pole switch
  • D
    Can be any of these
Answer
Correct option: C.
Double pole switch
(c)
Double pole switch
Explanation:
A double pole switch controls two circuits simultaneously by disconnecting both the live and neutral wires when turned off, enhancing safety by ensuring complete disconnection from the power source.
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MCQ 111 Mark
The neutral and earth wires are connected at the local substation so that
Answer
Correct option: B.
(b)
The neutral and earth wires are at the same potential
Explanation:
Connecting the neutral and earth wires at the same potential stabilizes the electrical system and safely directs any fault currents to the ground, reducing electric shock risks .
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MCQ 121 Mark
The voltage at which power is transmitted from generating stations to the main substation is:
  • A
    33 kV
  • B
    11 kV
  • ✓
    132 kV
  • D
    None of these
Answer
Correct option: C.
132 kV
(c)
132 kV
Explanation:
Power is transmitted at a high voltage of 132 kV from generating stations to main substations to minimize energy loss as heat in the transmission lines.
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MCQ 131 Mark
According to the old convention the colour of the earth wire is:
  • A
    black
  • ✓
    green
  • C
    yellow
  • D
    red
Answer
Correct option: B.
green
(b)
green
Explanation:
In old convention, colour code of wiring for live wire, earth wire and neutral wire are red, green and black respectively.
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MCQ 141 Mark
A circuit has 5 A fuse. The number of bulbs of rating $100 W, 220 V$ can be used in this circuit is ________ .
  • A
    5
  • B
    7
  • C
    9
  • ✓
    11
Answer
Correct option: D.
11
(d)
11
Explanation :
$
\begin{array}{l}
I=\frac{P \times n}{V} \\
5=\frac{100 \times n}{220} \\
n=11
\end{array}
$
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MCQ 151 Mark
The number of bulbs of 55 W each can be used in the house at normal voltage, when the main power supply of the house is through 2 A fuse...
  • A
    5
  • B
    6
  • C
    7
  • ✓
    8
Answer
Correct option: D.
8
(d) 8
Explanation :
Current in each bulb,
$I =\frac{ P }{ V }=\frac{55}{220}=0.25 A$
Number of bulb $=\frac{ I _{\text {Max }}}{ I _{\text {Bulb }}}$
$=\frac{2}{0.25}=8 \approx 8 bulbs$
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MCQ 161 Mark
Consider the following figure and answer the following answer?
Image
1. Step down transformer (City substation)
2. Step down transformer (Intermediate substation)
3. Step-up transformer
Choose the correct option?
  • A
    a-1, b-2, c-3
  • B
    a-1, b-3, c-2
  • ✓
    a-3, b-2, c-1
  • D
    a-3, b-1, c-2
Answer
Correct option: C.
a-3, b-2, c-1
(c)
a-3, b-2, с-1
Explanation:
'a' represents the grid substation, where the voltage is stepped up to 132 kV by a step-up transformer. 'b' represents the intermediate substation, where the voltage is stepped down to 11 kV by a step-down transformer. 'c' represents the city sub-station, where the voltage is stepped down to 220 V by a step-down transformer.
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MCQ 171 Mark
There are 2 rooms, A and B in a house, Each room has 2 lights and 2 fans. It was found that when in roon A one light fuses, the other appliances continue to glow, whereas for room B when one light fures, the other appliances also stops to operate. Which of the following is responsible for this?
  • A
    Room temperature of A and B
  • B
    Current Dow in the respective circuit of each room.
  • ✓
    Parallel and series connection
  • D
    Power supply to each room
Answer
Correct option: C.
Parallel and series connection
(c)
Parallel and series connection.
Explanation:
When one of the lights in room A goes out, the other appliances continue to work. This is due to the fact that in room A, all of the equipment are connected in parallel. However, because the equipment in room B are connected in series, once one is blown, all of them stop working.
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MCQ 181 Mark
Consider the following figure and answer the following question?
Image
What is the key ditierence between 'Fuse' and 'Circuit breaker'?
Answer
Correct option: A.
Permanent melting of swire and metching mechanism.
(a)
Permanent melting of wire and switching mechanism.
Explanation:
Fuses and circuit breakers are both meant to stop electricity from flowing. They do so. however, through different ways. When the fuse is overheated, it acts like a piece of metal that melts. When an overflow of electricity is detected, a circuit breaker activates a switching mechanism.
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MCQ 191 Mark
Answer
Correct option: C.
(c)
Switches are connected in parallel, so he/she nood 3 switches,
Explanation:
Switches are connected in parallel so that it he/she wants to turn off ane bullt, he/she can do so by turning off the appropriate switch. When the bulbs are connected in series, turning off one switch swill turn off all of them. That is why he/she had to buy a switches for 3 hulbs to control them separately.
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MCQ 201 Mark
The potential difference between the neutral wire and live wire is _________ .
  • A
    0 V
  • B
    110 V
  • ✓
    220 V
  • D
    440 V
Answer
Correct option: C.
220 V
(c)
220 V
Explanation:
We know that the earth and neutral wires are kept at 0 volt, while the live wire is kept at 220 volts. As a result, the voltage difference between the neutral and live wire is $220-0=220 V$. Similarly, there is a 220 V potential differential between the earth wire and the live wire.
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MCQ 211 Mark
Which of the following is correct?
  • A
    As the radius of the filament wire increases the fuse temperature rises above its surrounding.
  • B
    As the radius of the filament wire increases the fuse temperature drops below its surrounding.
  • C
    As the current flowing through the filament wire increases the fuse temperature rises above its surrounding.
  • ✓
    Both (b) and (c) are correct.
Answer
Correct option: D.
Both (b) and (c) are correct.
(d)
Both (b) and (c) are correct.
Explanation:
Options (b) and (c) can be checked by the following equation,
$
\Delta T \propto \frac{I^2}{r^2},
$
where $\Delta T$ is the temperature difference between the surrounding and the filament, I is the current flowing through the filament, and $r$ is the radius of the filament wire.
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MCQ 221 Mark
At where 'ring system' is used?
  • ✓
    House wiring
  • B
    Transmission line
  • C
    Power plant
  • D
    Only option (b) and (c) are correct.
Answer
Correct option: A.
House wiring
(a)
House wiring
Explanation:
The 'ring system' is typically used in house wiring to provide a redundant path for electrical current, enhancing safety and reliability, it is not commonly used in transmission lines or power plants.
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MCQ 231 Mark
Using the step up transformer the alternating voltage generated is first stepped up from $X kV$ to Y kV . Regarding this, which of the following is correct?
  • A
    $X =11, Y =220$
  • B
    $X =110, Y =132$
  • C
    $X =110, Y =760$
  • ✓
    $X =11, Y =132$
Answer
Correct option: D.
$X =11, Y =132$
(d)
$X=11, Y=132$
Explanation:
The alternating voltage generated is first stepped up from 11 kV to 132 kV . After that at the sub-station, using the step-down transformer this 132 kV is reduced to 33 kV . Similarly this again in the same manner it is reduced to 11 kV , then 220 V and finally reaches to the consumer households.
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MCQ 241 Mark
An electrical motor with a power rating of 10 kW and a voltage of 220 V . Is it possible to use a 50 A fuse for it?
  • ✓
    Yes
  • B
    No
  • C
    If the power of the motor is decreased by 5 kW , then only it's possible
  • D
    Cannot be said as it depends upon many other factors
Answer
Correct option: A.
Yes
(a)
Yes
Explanation:
The safe limit of current for the motor is
$
(I)=\frac{P}{V}=\frac{10,000}{220}=45.45 A .
$
As it is less than the current rating of the fuse, thus the fuse can be used safely.
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MCQ 251 Mark
An industrial electric equipment of power 10 kW is to be operated at mains of 280 volt. The current rating of the fuse to be connected with the motor should be?
  • A
    24 A
  • ✓
    35.71 A
  • C
    38.54 A
  • D
    48 A
Answer
Correct option: B.
35.71 A
(b)
35.71 A
Explanation:
Power P is given as $=10 kW=10000 W$
Mains voltage $=280 V$
Current drawn by the equipment,
$
\begin{array}{l}
I=\frac{P}{V}=\frac{10,000}{280} \\
=35.71 A .
\end{array}
$
Thus, the current rating of the fuse to be connected with the motor is 35.71 A .
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MCQ 261 Mark
At the power stations, ideally the electric power is produced at ______________ .
  • A
    1100 kV
  • B
    1000 kV
  • ✓
    11 kV
  • D
    10 kV
Answer
Correct option: C.
11 kV
(c)
11 kV
Explanation:
Ideally at 11 kV , the electric power is produced at the power stations. Then by subsequent step-up and step-down transformers this power is increased and decreased, finally it reaches to the consumer houses. In reality, it is little more than 11 kV .
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MCQ 271 Mark
An electrical fan of resistance $50 \Omega$ and draws a current of 0.2 A from a source. The power of fan is __________ .
  • ✓
    2 W
  • B
    4 W
  • C
    6 W
  • D
    10 W
Answer
Correct option: A.
2 W
(a)
2 W
Explanation:
$
\begin{array}{l}
P=I V=I^2 R \\
=(0.2)^2 \times 50 \\
=2 W
\end{array}
$
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MCQ 281 Mark
The power rating on bulb is 200 W and the voltage across this is 100 V . The current in the circuit will be ___________ .
  • A
    200 A
  • B
    20 A
  • ✓
    2 A
  • D
    1 A
Answer
Correct option: C.
2 A
(c)
2 A
Explanation :
$
I=\frac{P}{V}=\frac{200}{100}=2 A
$
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MCQ 291 Mark
Power rating of a heater is $200 W, 220 V$. The value of resistance of heater is __________ .
  • A
    $484 \Omega$
  • B
    $749 \Omega$
  • ✓
    $242 \Omega$
  • D
    $380 \Omega$
Answer
Correct option: C.
$242 \Omega$
(c)
$242 \Omega$
Explanation:
$
\begin{array}{l}
P=IV=\frac{V^2}{R} \\
R=\frac{V^2}{R}=\frac{(220)^2}{200}=242 \Omega
\end{array}
$
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MCQ 301 Mark
A house has main fuse of 10 A rating 6 bulbs each of 120 W and 2 fans each of 60 W are used. The current drawn from the mains of 210 V will be ______________ .
  • A
    2 A
  • ✓
    4 A
  • C
    6 A
  • D
    8 A
Answer
Correct option: B.
4 A
(b)
4 A
Explanation:
$
\begin{array}{l}
P=(6 \times 120)+(2 \times 60) \\
=720+120=840 W \\
V=210 V \\
I=\frac{P}{V}=\frac{840}{210}=4 A
\end{array}
$
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MCQ 311 Mark
When a bulb is powered by a 4 A current, the temperature difference between the filament and the surrounding air is $20^{\circ} C$. What current would result in a temperature difference of $100^{\circ} C$ ?
  • A
    2 A
  • B
    4 A
  • C
    4.5 A
  • ✓
    4.67 A
Answer
Correct option: D.
4.67 A
(d)
4.67 A
Explanation:
We know temperature difference $\Delta T \propto I ^2$, when filament, surrounding temperature are fixed.
Now, $20^{\circ} C =273+20=293 K ; 100^{\circ} C =273+100=373 K$.
So, we can write, $\frac{293}{373}=\frac{4^2}{\left(1_2\right)^2}$
or $I _2=4.67 A$.
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MCQ 321 Mark
Three electrical appliances with power $5 W, 10 W$ and 20 W are used for 5 hours, 10 hours, and 8 hours respectively. The total energy consumption is ____________ .
  • A
    225 Wh
  • B
    250 Wh
  • ✓
    285 Wh
  • D
    200 Wh
Answer
Correct option: C.
285 Wh
(c)
285 Wh
Explanation:
Power consumption in 1st appliances
$
=5 \times 5=25 Wh
$
Power consumption in 2nd appliances
$
=10 \times 10=100 Wh
$
Power consumption in 3rd appliances
$
=20 \times 8=160 Wh
$
Total energy consumption
$
\begin{array}{l}
=(25+100+160) \\
=285 Wh
\end{array}
$
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MCQ 331 Mark
The relationship between heat produced in wire $( H )$ and current (I) passing through it is :
  • A
    $H \propto I$
  • B
    $H \times \frac{1}{1}$
  • ✓
    $H \propto I ^2$
  • D
    $H \propto \frac{1}{I^2}$
Answer
Correct option: C.
$H \propto I ^2$
(c)
$H \propto I ^2$
Explanation:
Joule's law of heating says that the heat produced in a wire is directly proportional to the square of current passing through it.
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MCQ 341 Mark
In a house 2 fans of 60 W and 2 bulbs of 40 W each are used simultaneously the current drawn from 110 V will be _____________ .
  • ✓
    1.82 A
  • B
    30.81 A
  • C
    10.81 A
  • D
    2.31 A
Answer
Correct option: A.
1.82 A
(a)
1.82 A
Explanation:
Total power of appliances used simultaneously
$
\begin{array}{l}
P=(2 \times 60)+(2 \times 40) \\
=120+80=200 W
\end{array}
$
Voltage of mains, $V =110 V$
Current I $=\frac{ p }{ V }=\frac{200}{110}=1.82 A$
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MCQ 351 Mark
To light a bulb in a typical home, two long wires are connected to it. Despite the fact that the same current flows through both the wires and the filament, only the filament lights up. Why?
  • A
    Because filament is made of an alloy.
  • ✓
    Because length and cross-sectional area of the wires are large compared to filament wire.
  • C
    Because filament is good conductor of heat.
  • D
    None of the above.
Answer
Correct option: B.
Because length and cross-sectional area of the wires are large compared to filament wire.
(b)
Because length and cross-sectional area of the wires are large compared to filament wire.
Explanation:
The resistance of the wires is lower than filament wire because the length and cross-sectional area of the wires are both large. As a result, the wires are more difficult to heat up. The wire does not produce much heat, and hence does not produce much light.
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MCQ 361 Mark
Two fans A and B are rated at $100 W, 100 V$ and $50 W, 100 V$ respectively, are connected in parallel across 100 V source. Current in bulb A is ___________ .
  • A
    100 A
  • ✓
    1A

  • C
    3A
  • D
    5A
Answer
Correct option: B.
1A

(b)
1 A
Explanation:
$
\begin{array}{l}
R_{A}=\frac{V^2}{P_{A}}=\frac{(100)^2}{100}=100 \Omega \\
I_{A}=\frac{V}{R_{A}}=\frac{100}{100}=1 A
\end{array}
$
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MCQ 371 Mark
The safe current that can be pass through a bulb of $210 V, 3000 W$ is _________ .
  • A
    52.9 A
  • B
    4.35 A
  • ✓
    14.29 A
  • D
    9A
Answer
Correct option: C.
14.29 A
(c)
14.29 A
Explanation:
Given, $V =210 V$
$P =3000 W$
Safe current = ?
Since, $P = VI$
$
I=\frac{P}{V}=\frac{3000}{210}=14.29 A
$
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MCQ 381 Mark
40 watt-hour is equivalent to which of the following?
  • ✓
    $1.44 \times 10^5 J$
  • B
    $4.00 \times 10^5 J$
  • C
    $4.44 \times 10^5 J$
  • D
    $8.0 \times 10^5 J$
Answer
Correct option: A.
$1.44 \times 10^5 J$
(a)
$1.44 \times 10^5 J$
Explanation:
40 watt hour $=40 \times 3600 W- s =144000 W- s =1.44 \times 10^5 J$. Thus A is the correct option.
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MCQ 391 Mark
Source $A$ supplies $W_A$ amount of energy for a current of $2 A$ for 30 minutes, whereas source $B$ supplies $W_B$ amount of energy for the same amount of current for the same time. If the ratio of $W_A$ to $W_B$ is $1: 3$, what is the corresponding voltage ratio ( $V_A$ : $V_B$ )?
  • A
    $1: 2$
  • B
    $2: 1$
  • ✓
    $1: 3$
  • D
    $3: 1$
Answer
Correct option: C.
$1: 3$
(c)
$1: 3$
Explanation:
We know, $W = VI t$. Here, I and $t$ is same for both the cases. So, $\frac{ V _{ A }}{ V _{ B }}=\frac{ W _{ A }}{ W _{ B }}=\frac{1}{3}$.
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MCQ 401 Mark
Two resistance of $R _1=3 \Omega, R _2=8 \Omega$ are connected in parallel across battery of 20 V . Electrical energy supplied in 5 min ____________ .
  • A
    300 kJ
  • ✓
    277.49 kJ
  • C
    500.29 kJ
  • D
    600.37 kJ
Answer
Correct option: B.
277.49 kJ
(b)
277.49 kJ
Explanation:
Total resistance
$
\frac{1}{R}=\frac{1}{R_1}+\frac{1}{R_2}=\frac{1}{3}+\frac{1}{8}
$
$
R=\frac{3 \times 8}{8+3}=\frac{24}{11}=2.18 \Omega
$
Total current $( I )=\frac{ V }{ R }=\frac{20}{2.18}=9.17 A$
Energy consumed by $R _1$ is $W _1$
$
\begin{array}{l}
=I^2 R_1 t \\
=(9.17)^2 \times 3 \times 300 \\
=75.68 kJ
\end{array}
$
Energy consumed by $R _2$ is $W _2$
$
\begin{array}{l}
=I^2 R_2 t \\
=(9.17)^2 \times 8 \times 300 \\
=201.81 kJ
\end{array}
$
Total energy supplied $= W _1+ W _2$
$
=75.68+201.81
$
$=277.49 kJ$
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MCQ 411 Mark
The amount of heat produce in 1 hour in a electric heater rated $500 W, 300 V$.
  • A
    $50 \times 10^5 J$
  • B
    $36 \times 10^5 J$
  • ✓
    $18 \times 10^5 J$
  • D
    300 J
Answer
Correct option: C.
$18 \times 10^5 J$
(c)
$18 \times 10^5 J$
Explanation:
Heat produced in time $t=$ Power $\times$ Time
$
\begin{array}{l}
=500 \times(60 \times 60) \\
=18 \times 10^5 J
\end{array}
$
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MCQ 421 Mark
A current is flowing through a voltage source in a resistor of $30 \Omega$ for 5 minutes. The heat produced will be ____________ .
  • A
    $9 \times 10^3 cal$
  • ✓
    $1.9 \times 10^4 cal$
  • C
    $4 \times 10^5 cal$
  • D
    19.44 cal
Answer
Correct option: B.
$1.9 \times 10^4 cal$
(b)
$1.9 \times 10^4 cal$
Explanation:
Given I = 3A
$
\begin{array}{l}
R=30 \Omega \\
t=5 min=300 \text { seconds } \\
\text { Heat produced in resistor }=I^2 R t J \\
=0.24 \times 3 \times 3 \times 30 \times 300 \text { calorie } \\
=19440 cal \\
=1.9 \times 10^4 cal
\end{array}
$
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MCQ 431 Mark
Electrical power can be written as $P =\frac{ QV }{t}$.
  • A
    VI
  • B
    $I^2 R$
  • C
    $\frac{ VQ }{ t }$
  • ✓
    All of these
Answer
Correct option: D.
All of these
(d)
All of these
Explanation:
$P =\frac{\text { Energy supplied }( E )}{\text { Time }(t)}$
$P =\frac{ VIt }{t}= VI$
But $I =\frac{ Q }{t}$
$P =\frac{ QV }{t}$
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