JKSSB Electrician 2025 Solved Question Paper

Question 1

Fill in the blank using a suitable article:
_____ unique artist often develops _____ signature style that distinguishes them and their work from their peers.

Accepted Answer

Option D: A, a. 'Unique' begins with a consonant 'y' sound (/juː/), taking indefinite article 'A'. 'Signature style' takes indefinite article 'a': 'A unique artist often develops a signature style...'.

Question 2

Select the Synonyms of the word: Jabber

Accepted Answer

Option A: Prattle. 'Jabber' means to talk rapidly, indistinctly, or nonsensically. Its direct synonym is 'Prattle' (or chatter).

Question 3

Select the Antonym of the word: Byzantine

Accepted Answer

Option C: Candid. 'Byzantine' describes something excessively complicated, devious, or convoluted. Its antonym is 'Candid' (or simple, straightforward, transparent).

Question 4

What is one of the primary reasons for the increasing vulnerability of networks in today's digital landscape?

Accepted Answer

Option B: The rapid increase of IoT devices. According to the passage, 'The proliferation of Internet of Things (IoT) devices has expanded the attack surface by making networks more susceptible to unauthorized access.'

Question 5

In the context of cybersecurity, what does the term 'social engineering' refer to?

Accepted Answer

Option D: Manipulating individuals into revealing confidential information. Social engineering in cybersecurity refers to the psychological manipulation of human individuals to trick them into divulging sensitive passwords, credentials, or confidential information.

Question 6

Which of the following is the correct spelling of the word that means "the action of throwing someone out of a window"?

Accepted Answer

Option A: Defenestration. The correct spelling is 'Defenestration' (from Latin fenestra, meaning window).

Question 7

Which of the following is the correct spelling of the word that means "excessively talkative"?

Accepted Answer

Option D: Garrulous. The correct spelling is 'Garrulous' (meaning excessively talkative, especially on trivial matters).

Question 8

Choose the pair of words that will make the sentence grammatically correct and meaningful.
The facilitator _____ the advantages of collaborative tasks to _____ learners teamwork skills.

Accepted Answer

Option A: emphasized, enhance. 'The facilitator emphasized the advantages of collaborative tasks to enhance learners teamwork skills' is idiomatic and grammatically precise.

Question 9

The abstract noun in the below sentence is:
It requires immense determination to pursue your dreams despite obstacles.

Accepted Answer

Option B: determination. 'Determination' is an abstract noun denoting the quality of being resolute and firmness of purpose.

Question 10

The indefinite pronoun in the below sentence is:
Mohan in the audience expressed concern about whether anything could be done to improve the situation.

Accepted Answer

Option D: anything. 'Anything' is an indefinite pronoun referring to an unspecified thing or matter.

Question 11

Fill in the blank using suitable homophones:
Despite the _____ remarks made by the coach, the athlete continued to train hard and developed a _____ on her hand by gripping the weights.

Accepted Answer

Option C: callous, callus. 'Callous' (adjective) means insensitive, unfeeling, or harsh. 'Callus' (noun) means a thickened and hardened part of the skin caused by friction.

Question 12

The form of tense used in the below sentence is:
By the time the conference starts, the researchers will have been studying the effects of climate change on biodiversity for the next five years.

Accepted Answer

Option D: Future Perfect Continuous Tense. The construction 'will have been studying' represents the Future Perfect Continuous Tense (will + have + been + present participle), describing an ongoing action extending up to a future point.

Question 13

Let p(x) is a polynomial of degree 6 in the form of a1*x^6 + a2*x^5 + ... + a6*x + a7. It has only one root at x = -1, that is p(-1) = 0. Find the value of a2 and a3 respectively.

Accepted Answer

Option B: 15, 20. A degree-6 monic polynomial with only root at $x = -1$ has the form $(x+1)^6 = x^6 + 6x^5 + 15x^4 + 20x^3 + 15x^2 + 6x + 1$. Its successive binomial coefficients are $15, 20$.

Question 14

A girl is playing with a sequence of three numbers, each of which is the square of consecutive natural numbers. When the largest number is removed, then the average of the remaining numbers decreases by 37/6 as compared to the original average. What is the value of the largest square in the old sequence?

Accepted Answer

Option A: 49. Let the consecutive numbers be $n, n+1, n+2$. The original average of their squares:
$$A_1 = \frac{n^2 + (n+1)^2 + (n+2)^2}{3} = \frac{3n^2 + 6n + 5}{3}$$
When $(n+2)^2$ is removed, the average of $n^2$ and $(n+1)^2$ is:
$$A_2 = \frac{n^2 + (n+1)^2}{2} = \frac{2n^2 + 2n + 1}{2}$$
$$A_1 - A_2 = \frac{2(3n^2 + 6n + 5) - 3(2n^2 + 2n + 1)}{6} = \frac{6n + 7}{6}$$
Given $\frac{6n + 7}{6} = \frac{37}{6} \implies 6n + 7 = 37 \implies 6n = 30 \implies n = 5$.
The numbers are 5, 6, 7. The largest square is $7^2 = 49$.

Question 15

Fresh food contains 40% water, whereas dried food contains only 24% water. Starting with 100 kg of fresh food, how much dried food can be produced?

Accepted Answer

Option C: 78.9. 100 kg of fresh food contains $100 - 40 = 60	ext{ kg}$ of dry solid pulp.
In dried food, solids constitute $100 - 24 = 76\%$.
$$	ext{Weight of dried food} 	imes 0.76 = 60 \implies 	ext{Weight} = \frac{60}{0.76} \approx 78.9	ext{ kg}.$$

Question 16

Three co-prime numbers a, b, c satisfy the following conditions:
LCM(a,b) = 437
LCM(b,c) = 667
LCM(a,c) = 551
Find the value of a + b + c

Accepted Answer

Option C: 71. Since $a, b, c$ are pairwise co-prime prime factors:
- $ab = 437 = 19 	imes 23$
- $bc = 667 = 23 	imes 29$
- $ac = 551 = 19 	imes 29$
Thus $a = 19, b = 23, c = 29$.
$$a + b + c = 19 + 23 + 29 = 71.$$

Question 17

A bike was bought for Rs 45,000 at a certain discount, and its value depreciates by 8% annually. At the end of the third year, it was written-off at its depreciated value, which is 45% of the bike's original undiscounted price. What is the original undiscounted price of the bike?

Accepted Answer

Option B: 77869. Depreciated value after 3 years:
$$V_3 = 45000 	imes (1 - 0.08)^3 = 45000 	imes (0.92)^3 = 45000 	imes 0.778688 = 35040.96	ext{ Rs}$$
Given $V_3 = 0.45 	imes P_{	ext{original}}$:
$$P_{	ext{original}} = \frac{35040.96}{0.45} \approx 77,868.8 \approx 77,869	ext{ Rs}.$$

Question 18

Two children are playing a game in which one child thinks of a three-digit number N, and the other child guesses it by asking for remainders when N is divided by certain numbers. The clues are:
1. The remainder when N is divided by 3 is 2.
2. The remainder when N is divided by 5 is 4.
3. The remainder when N is divided by 7 is 6.
4. The sum of the digits of N is 11.
Find the product of the digits of the smallest N that satisfies these conditions:

Accepted Answer

Option B: 0. From the remainder conditions: $N \equiv -1 \pmod{	ext{LCM}(3,5,7)} \implies N \equiv -1 (mod 105) \implies N = 105k - 1$.
- For $k = 1: N = 104$ (Sum of digits = 5)
- For $k = 2: N = 209$ (Sum of digits = $2 + 0 + 9 = 11$, matches condition 4!).
The smallest three-digit number is $N = 209$.
Product of digits $= 2 	imes 0 	imes 9 = 0$.

Question 19

A boy wanted to think of a large perfect square and guessed the number 98,765. However, it turned out that 98,765 is not a perfect square. Help him find the perfect square closest to 98,765.

Accepted Answer

Option A: 98596. $\sqrt{98765} \approx 314.269$.
- $314^2 = 98,596$ (difference = $98765 - 98596 = 169$)
- $315^2 = 99,225$ (difference = $99225 - 98765 = 460$).
The closest perfect square is $314^2 = 98596$.

Question 20

The ratio of the ages of three friends A, B, and C is 3:5:7. Eight years ago, the ratio of their ages was 1:3:5. Find their present ages.

Accepted Answer

Option A: 12, 20, 28. Let present ages be $3x, 5x, 7x$.
8 years ago:
$$\frac{3x - 8}{5x - 8} = \frac{1}{3} \implies 9x - 24 = 5x - 8 \implies 4x = 16 \implies x = 4$$
Present ages: $3(4) = 12, 5(4) = 20, 7(4) = 28	ext{ years}$.

Question 21

The average weight of a group of 10 boys is 52 kg. When a boy weighing 60 kg leaves the group and is replaced by another boy, the average weight of the group decreases by 0.5 kg. Determine the weight of the boy who replaced him.

Accepted Answer

Option B: 55 kg. Initial total weight $= 10 	imes 52 = 520	ext{ kg}$.
New total weight $= 10 	imes (52 - 0.5) = 10 	imes 51.5 = 515	ext{ kg}$.
Weight of new boy $= 60 + (515 - 520) = 60 - 5 = 55	ext{ kg}$.

Question 22

The LCM of two numbers is 120, and their HCF is 6. If the sum of the two numbers is 54, find the two numbers.

Accepted Answer

Option D: 24, 30. Let the numbers be $6a$ and $6b$ where $\gcd(a,b)=1$.
$6ab = 120 \implies ab = 20$.
$6(a + b) = 54 \implies a + b = 9$.
The co-prime factors of 20 that add up to 9 are 4 and 5.
The numbers are $6 	imes 4 = 24$ and $6 	imes 5 = 30$.

Question 23

Find the value of 5^1234 (mod 16)

Accepted Answer

Option C: 9. Modulo 16 powers of 5:
- $5^1 \equiv 5 (mod 16)$
- $5^2 = 25 \equiv 9 (mod 16)$
- $5^3 = 45 \equiv 13 (mod 16)$
- $5^4 = 65 \equiv 1 (mod 16)$.
Since $1234 = 4 	imes 308 + 2$:
$$5^{1234} \equiv (5^4)^{308} 	imes 5^2 \equiv 1^{308} 	imes 25 \equiv 9 (mod 16).$$

Question 24

What is the smallest natural value of a + b + c if a:b = 4:7 and b:c = 6:5?

Accepted Answer

Option D: 101. Combining the ratios:
$a:b = 4:7 = 24:42$
$b:c = 6:5 = 42:35$
Thus, $a:b:c = 24:42:35$.
Smallest natural sum $= 24 + 42 + 35 = 101$.

Question 25

Which of the following is NOT a type of non-linear resistor?

Accepted Answer

Option D: Wire-wound resistor. A wire-wound resistor is a linear resistor whose resistance follows Ohm's law ($V = IR$) proportionally. Thermistors, varistors (VDRs), and photoresistors (LDRs) are non-linear components whose resistance changes non-linearly with temperature, voltage, or light.

Question 26

In her house, Anita installed 4 new fans with each fan consuming 70 W in addition to the 6 fans already installed with each fan consuming 50 W. She uses the new fans for 10 hours daily and the older fans for 20 hours daily. Calculate the electricity bill for one month (30 days) if the cost of one unit of electricity is Rs. 10.

Accepted Answer

Option D: Rs. 2640. Daily energy consumption:
- New fans: $4 	imes 70	ext{ W} 	imes 10	ext{ h} = 2800	ext{ Wh} = 2.8	ext{ kWh}$
- Old fans: $6 	imes 50	ext{ W} 	imes 20	ext{ h} = 6000	ext{ Wh} = 6.0	ext{ kWh}$
- Daily total $= 2.8 + 6.0 = 8.8	ext{ kWh (units)}$
- Monthly units (30 days) $= 8.8 	imes 30 = 264	ext{ units}$
- Total bill $= 264 	imes 10 = 	ext{Rs. } 2640$.

Question 27

Which of the following statements is correct regarding non-ohmic conductors?

Accepted Answer

Option C: Non-ohmic conductors have a resistance that varies with current, voltage and temperature changes.. Non-ohmic conductors do not obey Ohm's law; their dynamic resistance changes non-linearly with applied voltage, current magnitude, or operating temperature (e.g. diodes, transistors, thermistors).

Question 28

Which of the following conditions could result in the violation of Kirchhoff's laws?

Accepted Answer

Option D: Influence of a varying magnetic field in the closed loop.. Kirchhoff's Voltage Law (KVL) assumes an irrotational electrostatic field ($\oint \vec{E} \cdot d\vec{l} = 0$). In the presence of a time-varying magnetic field inside the loop, Faraday's law applies ($\oint \vec{E} \cdot d\vec{l} = -d\Phi_B/dt 
eq 0$), causing apparent violation of KVL.

Question 29

Which of the following statements about Kirchhoff's first and second law is NOT correct?

Accepted Answer

Option B: Kirchhoff's first law is applicable to circuits with resistive components only.. Statement B is incorrect: Kirchhoff's Current Law (KCL, First Law) is universally applicable to any electrical junction or node in any network (linear, non-linear, AC, DC, capacitive, inductive, or resistive).

Question 30

The equivalent resistance of n resistors in parallel combinations will always be:

Accepted Answer

Option C: less than the least value of resistance in the combination. In a parallel combination, the equivalent resistance $R_{eq} = \left(\sum \frac{1}{R_i}\right)^{-1}$ is always strictly less than the smallest individual resistance in the combination.

Question 31

The resistance of the wire is 10 ohms. What will be the effect on resistance and resistivity of the wire, if the wire is stretched to 10 times its original length?

Accepted Answer

Option A: Resistance increases by 100 times, resistivity remains unchanged.. When a wire of length $L$ and area $A$ is stretched to $10L$, its volume $V = A \cdot L$ remains constant, so its cross-sectional area becomes $A/10$.
New resistance $R' = \rho \frac{10L}{A/10} = 100 \left(\rho \frac{L}{A}\right) = 100 R$.
Resistivity ($\rho$) is an intensive intrinsic material property and remains completely unchanged.

Question 32

When measuring the resistance of an earthing system, which of the following factors is/are most important for ensuring accurate readings?
1. Length/Depth of the earthing electrode
2. Distance between measurement points
3. Type of soil surrounding the electrode

Which of the above statements is/are correct?

Accepted Answer

Option D: All of the above. Accurate earth resistance testing (Fall-of-Potential method) depends critically on electrode insertion depth (1), proper auxiliary electrode spacing distances (2), and surrounding soil resistivity/composition (3) (All of the above).

Question 33

Which statement correctly differentiates between grounding and earthing in electrical systems?

Accepted Answer

Option B: Grounding connects electrical systems to the earth, while earthing refers to creating a reference point within the system.. Earthing connects non-current carrying metallic equipment enclosures directly to ground for personnel safety against shock, whereas Grounding provides a zero-potential reference point (such as neutral grounding) for system balancing.

Question 34

Which of the following statements correctly describes the principle of operation of an electric heater?
1. Electric heaters work by converting electrical energy into heat energy through a heating element or coil.
2. Electric heaters operate on the principle of electromagnetic induction to generate heat.
3. Electric heaters utilize the heating effect of electric current, where resistance in the heating element produces heat.
4. Electric heaters rely on chemical reactions in the filament or coil to produce heat for heating purposes.

Which of the above statements is/are correct?

Accepted Answer

Option B: Only 1 and 3. Electric heaters function via Joule's heating effect of electric current ($H = I^2 R t$), converting electrical energy directly into thermal heat energy across a resistive alloy coil (Statements 1 and 3 are correct).

Question 35

Which material is commonly used as the heating element in an electric iron and why is it preferred?

Accepted Answer

Option B: Nichrome, due to its high resistance and ability to withstand high temperatures. Nichrome (an alloy of 80% Nickel and 20% Chromium) is preferred because of its high electrical resistivity, high melting point (~1400°C), and formation of a protective chromium oxide layer that prevents oxidation at high temperatures.

Question 36

Match the different types of electric water heaters with their working principle:

Choose the correct option:

Accepted Answer

Option C: i-2, ii-3, iii-1. Matching: i) Normal plate heater uses spaced nickel plates (2); ii) Immersion heater features a copper/sheathed U-tube packed with magnesium oxide (MgO) insulation (3); iii) Storage geysers feature heavy-duty enclosed nichrome heating elements (1). Code: i-2, ii-3, iii-1.

Question 37

What is the primary function of the Fuzzy Inference Unit (FIU) in a fuzzy controller used in a washing machine?

Accepted Answer

Option C: To apply fuzzy logic rules for decision-making based on input conditions. The Fuzzy Inference Unit (FIU) processes fuzzified input sensor variables (such as load weight, fabric type, dirt level) by evaluating IF-THEN linguistic fuzzy rules to determine optimal wash duration, water level, and spin speed.

Question 38

What is the primary working principle of a washing machine?

Accepted Answer

Option B: Agitation - The process where clothes are moved vigorously in water to enhance cleaning.. The primary mechanical principle of a washing machine is agitation (or pulsator/tumbling motion) where vigorous mechanical turbulence forces water and detergent through fabric weave to dislodge dirt particles.

Question 39

Match the components in the refrigerator system with the corresponding functions:

Choose the correct option:

Accepted Answer

Option D: i-2, ii-3, iii-4, iv-1. Matching: i) Evaporator absorbs heat from inside compartment (2); ii) Compressor compresses low-pressure vapor into high-pressure vapor (3); iii) Condenser cools and condenses gas to liquid via rear fins (4); iv) Expansion valve drops pressure and regulates refrigerant flow (1). Code: i-2, ii-3, iii-4, iv-1.

Question 40

A surface is inclined at an angle of 45° to the rays and is kept 5 m away from a 150 candle power lamp. Calculate the average intensity of illumination on the surface. (Value of square root of 2 = 1.414)

Accepted Answer

Option A: 4.2 Lux. According to Lambert's Cosine Law of Illumination:
$$E = \frac{I \cos 	heta}{d^2} = \frac{150 	imes \cos 45^\circ}{5^2} = \frac{150 	imes \frac{1}{1.414}}{25} = \frac{6}{1.414} \approx 4.24	ext{ Lux} \approx 4.2	ext{ Lux}.$$

Question 41

Match the Lamp with its luminous efficiency:

Choose the correct option:

Accepted Answer

Option A: i-1, ii-4, iii-2, iv-3. Luminous efficiencies: Neon discharge (15-40 lm/W - 1); Low Pressure Sodium Vapour (101-175 lm/W - highest efficacy - 4); High Pressure Mercury Vapour (30-40 lm/W - 2); Fluorescent lamp (50-60 lm/W - 3). Code: i-1, ii-4, iii-2, iv-3.

Question 42

Consider the following statements about Hydroelectric Power:
1. Hydroelectric power is a secondary source of energy.
2. It is a non-renewable energy source that uses the force of flowing or falling water to drive turbines and generate electricity.
3. It is efficient and eco-friendly but can harm ecosystems and displace communities.

Which of the above statements is/are correct?

Accepted Answer

Option B: 1 and 3. Hydroelectric power generates electricity (a secondary energy carrier) (1 - True) and is clean during operation but has ecological/displacement impacts (3 - True). Statement 2 is false because water power is renewable (not non-renewable). Thus, 1 and 3 are correct.

Question 43

Which of the following is NOT a source of a magnetic field?

Accepted Answer

Option D: A stationary electric charge. A stationary electric charge ($q$ with $v=0$) produces only a static electrostatic field. Magnetic fields are produced only by moving charges, electric currents, or time-varying electric fields (Maxwell's displacement current).

Question 44

A cube is formed by 12 wires of equal length a, each carrying a current I amperes. What is the value of the magnetic field at the center of the cube?

Accepted Answer

Option C: Zero. Due to the symmetrical geometric distribution of currents along all 12 edges of the cube, the magnetic field vectors produced by opposite, symmetric pairs of wires cancel out pairwise at the geometric center, yielding a net magnetic field of Zero.

Question 45

A circular coil carrying a certain current produces a magnetic field B0 at its center. If the coil is rewound to have n turns while maintaining the same current, what will be the new magnetic field at the center of the new coil?

Accepted Answer

Option B: n B0. Magnetic field at center of a coil of $n$ turns: $B = n B_0$ (or proportional to $n^2$ when wire length is kept constant, here standard question paper specifies $n B_0$).

Question 46

Consider the following statements about Magnetic Field Lines in a Bar Magnet:
1. Outside the bar magnet, field lines are directed from the South Pole to the North Pole.
2. The lines form closed continuous curves and can never intersect with each other.
3. The magnetic field is strong where field lines are crowded and vice-versa.

Which of the above statements is/are correct?

Accepted Answer

Option C: 2 and 3. Statements 2 and 3 are correct. Statement 1 is false because outside a magnet, magnetic field lines emerge from the North pole and enter the South pole (they run South to North only inside the magnet).

Question 47

Why is the magnetic field at a point near the center but outside a current-carrying solenoid equal to zero?

Accepted Answer

Option A: The magnetic fields produced by adjacent turns of the solenoid cancel each other due to their opposite orientations and symmetry in the external region.. Outside an ideal long solenoid, the field vectors from opposite sides and adjacent turns point in opposite directions and destructively cancel each other out, resulting in a net external field of approximately zero.

Question 48

Why do two wires carrying current in the same direction attract each other, while two beams of electrons traveling in the same direction repel each other?

Accepted Answer

Option C: Current carrying wires experience attractive magnetic forces whereas electron beams experience electrostatic repulsion forces.. Current-carrying wires are electrically neutral (equal positive ions and electrons), so there is zero net electrostatic force, and magnetic attraction dominates. In electron beams, there are no neutralizing positive ions, so immense electrostatic Coulomb repulsion vastly exceeds magnetic attraction.

Question 49

Two long parallel wires carry currents I1 and I2, where I1 > I2. When both currents flow in the same direction, the magnetic field at a point midway between the wires is measured to be 70 μT. When the direction of I2 is reversed, the magnetic field at the same point increases to 140 μT. What is the value of I1 / I2?

Accepted Answer

Option D: 3:1. At the midpoint, when currents are parallel (same direction), fields oppose: $B = k(I_1 - I_2) = 70\ \mu	ext{T}$.
When anti-parallel (opposite direction), fields add: $B' = k(I_1 + I_2) = 140\ \mu	ext{T}$.
$$\frac{I_1 + I_2}{I_1 - I_2} = \frac{140}{70} = 2 \implies I_1 + I_2 = 2I_1 - 2I_2 \implies I_1 = 3I_2 \implies \frac{I_1}{I_2} = 3:1.$$

Question 50

Which option gives the correct arrangement of metals in the ascending order of their electrical conductivity?

Accepted Answer

Option D: Aluminum > Gold > Copper > Silver. Electrical conductivity values (highest to lowest): Silver (105%) > Copper (100%) > Gold (70%) > Aluminum (61%). Arranged in ascending order (lowest to highest): Aluminum < Gold < Copper < Silver.

Question 51

Which of the following statements are NOT correct regarding Hard Magnets?

Accepted Answer

Option B: The hysteresis loop area, retentivity and coercivity are small for hard magnets.. Statement B is incorrect: Hard magnetic materials have a LARGE hysteresis loop area, HIGH coercivity, and HIGH retentivity (making them ideal for permanent magnets). Soft magnetic materials have small loop areas.

Question 52

Consider the following statements about the Hysteresis Loop:
1. A hysteresis loop is generated by measuring the magnetic flux emitted from a ferromagnetic material as the external magnetic field applied to it is varied.
2. The hysteresis loop shows the relationship between the magnetic flux density and the magnetizing field strength of a paramagnetic substance.
3. The loss of energy per unit volume of the substance is equal to the area of the hysteresis curve.

Which of the above statements is/are correct?

Accepted Answer

Option B: 1 and 3. Statements 1 and 3 are correct. Statement 2 is false because hysteresis loops (B-H curves) are exhibited by Ferromagnetic materials, NOT paramagnetic substances.

Question 53

Which of the following statements about soft iron and steel in the context of their magnetic properties is NOT correct?

Accepted Answer

Option D: Steel is preferred for use in transformers because of its high coercivity and low permeability.. Statement D is incorrect: Transformer cores require high magnetic permeability and low coercivity/hysteresis loss; therefore, silicon steel or soft iron is used, NOT high-coercivity steel.

Question 54

Which of the following is NOT a practical application of electromagnetic induction?

Accepted Answer

Option A: Printers and Photocopy Machines. Printers and photocopy machines work on electrostatic charge attraction (Xerography / photoconductivity), NOT electromagnetic induction.

Question 55

Why is a spark produced in the fan switch when it is turned off?

Accepted Answer

Option C: The collapsing magnetic field around the fan coil induces a back electromotive force (EMF), which ionizes the air around the switch.. When an inductive circuit is opened, the abrupt collapse of magnetic flux induces a massive self-induced back EMF ($e = -L di/dt$) across the opening switch contacts, breaking down and ionizing the air gap to produce a spark.

Question 56

A coil has a self-inductance of 5 mH. If the current through the coil increases from 0 to 2 A in 0.2 s, what is the magnitude and direction of the induced EMF?

Accepted Answer

Option B: 0.05 V, in the opposite direction of the current change. By Lenz's Law and Faraday's Law:
$$e = -L \frac{\Delta I}{\Delta t} = - (5 	imes 10^{-3}	ext{ H}) 	imes \frac{2 - 0}{0.2} = - 5 	imes 10^{-3} 	imes 10 = -0.05	ext{ V}$$
Magnitude is 0.05 V, opposing the direction of current change.

Question 57

Which of the following is NOT a practical application of eddy currents?

Accepted Answer

Option D: create airtight seals on containers. Induction furnaces, eddy current train brakes, and drag-cup speedometers directly rely on eddy currents. Creating airtight mechanical seals on containers is a mechanical process.

Question 58

Consider the following statements about Fleming's rules:
1. Fleming's Left-Hand Rule is used to determine the direction of force in an electric motor when a current-carrying conductor is placed in a magnetic field.
2. Fleming's Right Hand Rule is used to identify the direction of induced current when a conductor moves within a magnetic field which is essential for understanding generator functions.
3. Both of Fleming's rules have practical applications in various electromagnetic devices such as relays, loudspeakers, microphones, galvanometers, and maglev systems.

Which of the above statements is/are correct?

Accepted Answer

Option D: 1, 2 and 3. All three statements are correct: Fleming's Left-Hand Rule applies to Motors (FBI: Force, B-field, Current), Fleming's Right-Hand Rule applies to Generators (Induced Current), and both have broad electromagnetic applications.

Question 59

Direct current (DC) is used in which of the following devices?

Accepted Answer

Option C: Cordless drills and tools. Cordless power tools and drills operate on portable rechargeable DC battery packs (typically Li-ion 12V/18V/20V DC motors).

Question 60

In an AC circuit, the instantaneous emf and current are given by:
E = 120 sin(50t) and I = 15 sin(50t - pi/3)
What is the average power consumed by the circuit (in watts) and the wattless current (in amperes)?

Accepted Answer

Option A: 450 W, 7.5*sqrt(3/2) A. $E_{	ext{rms}} = \frac{120}{\sqrt{2}}$, $I_{	ext{rms}} = \frac{15}{\sqrt{2}}$, and phase angle $\phi = \frac{\pi}{3} = 60^\circ$.
- Average Power $P = E_{	ext{rms}} I_{	ext{rms}} \cos \phi = \left(\frac{120}{\sqrt{2}}ight) \left(\frac{15}{\sqrt{2}}ight) \cos 60^\circ = 900 	imes 0.5 = 450	ext{ W}$.
- Wattless Current $I_w = I_{	ext{rms}} \sin \phi = \frac{15}{\sqrt{2}} \sin 60^\circ = \frac{15}{\sqrt{2}} 	imes \frac{\sqrt{3}}{2} = 7.5 \sqrt{\frac{3}{2}}	ext{ A}$.

Question 61

What is the possible range for the power factor in AC circuits?

Accepted Answer

Option A: 0 to 1. In AC power systems, power factor $\cos \phi = \frac{P}{S}$ ranges from 0 (purely inductive or capacitive load) to 1 (purely resistive unity power factor load).

Question 62

Which of the following is NOT the cause of the low power factor?

Accepted Answer

Option D: Inductive loads draw a current that leads the voltage.. Inductive loads (like induction motors and transformers) draw a current that LAGS the voltage (not leads). Capacitive loads draw leading current.

Question 63

Which of the following statements is/are correct regarding the advantages of 3-phase system over a single-phase system?
1. In a 3-phase power supply system, less voltage drop occurs from the source to the load points in comparison to a single-phase transmission system.
2. A 3-phase system requires less copper and aluminum for the transmission system in comparison to a single-phase transmission system.
3. A pulsating torque is produced in a 3-phase system, whereas in a single-phase system uniform or constant torque is produced.

Which of the above statements is/are correct?

Accepted Answer

Option A: 1 and 2. 3-phase systems provide reduced line voltage drop (1) and require ~75% conductor copper/aluminum material for the same power delivery compared to single-phase (2). Statement 3 is false because 3-phase machines produce steady constant rotating torque, whereas single-phase machines produce pulsating torque. Thus, 1 and 2 are correct.

Question 64

Match the different schematic electronic symbols with their names:

![Electronic Schematic Symbols](/images/questions/electrician_2025/jkssb_electrician_2025_q64.png)

Choose the correct option:

Accepted Answer

Option C: i-4, ii-2, iii-1, iv-3. i) Symbol (i) is a Darlington Pair Transistor configuration (4);
ii) Symbol (ii) is a PMOS Field Effect Transistor (2);
iii) Symbol (iii) is a 2-to-1 Multiplexer (MUX) with inputs I0, I1 and select line A (1);
iv) Symbol (iv) is a 1-to-2 Demultiplexer (DEMUX) with input I and outputs D0, D1 (3).
Correct matching code is i-4, ii-2, iii-1, iv-3.

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Fill in the blank using a suitable article:
_ unique artist often develops _ signature style that distinguishes them and their work from their peers.

Choose the pair of words that will make the sentence grammatically correct and meaningful.
The facilitator _ the advantages of collaborative tasks to _ learners teamwork skills.

The abstract noun in the below sentence is:
It requires immense determination to pursue your dreams despite obstacles.

The indefinite pronoun in the below sentence is:
Mohan in the audience expressed concern about whether anything could be done to improve the situation.

Fill in the blank using suitable homophones:
Despite the _ remarks made by the coach, the athlete continued to train hard and developed a _ on her hand by gripping the weights.

The form of tense used in the below sentence is:
By the time the conference starts, the researchers will have been studying the effects of climate change on biodiversity for the next five years.

Three co-prime numbers a, b, c satisfy the following conditions:
LCM(a,b) = 437
LCM(b,c) = 667
LCM(a,c) = 551
Find the value of a + b + c

In an AC circuit, the instantaneous emf and current are given by:
E = 120 sin(50t) and I = 15 sin(50t - pi/3)
What is the average power consumed by the circuit (in watts) and the wattless current (in amperes)?

Poor power factor can result in:
1. Heat damage to insulation and other circuit components
2. Reduction in the amount of available useful power
3. A required increase in conductor and equipment sizes

Choose the correct option: