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Past Questions
In a rectangle, if the angle between a diagonal and a side is 30° and the length of the diagonal is 6cm, then the area of the rectangle is:
A)
9 cm²
B)
27 cm²
C)
36 cm²
D)
9√3 cm²
Let the diagonal of the rectangle be 6 cm and the angle between the diagonal and one side be 30°. The diagonal forms a right triangle with the length and breadth of the rectangle as perpendicular sides.
Using trigonometry:
- One side = 6 cos 30° = 6 × (√3/2) = 3√3 cm
- Other side = 6 sin 30° = 6 × (1/2) = 3 cm
Area of rectangle = length × breadth = (3√3) × 3 = 9√3 cm².
So, the correct answer is option (d). The other options do not match the product of the two sides obtained from the given diagonal and angle.
If the second and the third digits of each number given below are interchanged, which number will be [incomplete question]
Answer: cannot be determined from the provided question/options
The question is incomplete: it says, 'If the second and the third digits of each number given below are interchanged, which number will be [incomplete question]' but the actual numbers/options are missing (the options field is empty: {}). Without the list of numbers or answer choices, the correct option cannot be identified. Please provide the full question and options so the digit-swap comparison can be performed.
A man invested a certain amount at the rate of 12% simple interest and a certain amount at the rate of 10% simple interest. He received yearly interest of Rs. 130. But if he had interchanged the amounts invested, he would have received Rs. 4 more as interest. How much did he initially invest at 12% simple interest?
A)
400
B)
500
C)
600
D)
700
Let the amount invested at 12% be x and at 10% be y.
Given yearly interest:
0.12x + 0.10y = 130
If the amounts were interchanged, interest would be Rs. 4 more:
0.10x + 0.12y = 134
Subtract the first equation from the second:
(0.10x + 0.12y) - (0.12x + 0.10y) = 134 - 130
0.02y - 0.02x = 4
y - x = 200
So, y = x + 200.
Substitute into the first equation:
0.12x + 0.10(x + 200) = 130
0.12x + 0.10x + 20 = 130
0.22x = 110
x = 500
Thus, the amount initially invested at 12% is Rs. 500.
So the correct answer is option (b).
If Rs. 3000 amounts to Rs. 4320 at Compound Interest in a certain time, then Rs. 3000 amounts to what in half of the time?
A)
Rs. 3400
B)
Rs. 3600
C)
Rs. 3800
D)
Rs. 3520
At compound interest, if Rs. 3000 becomes Rs. 4320 in time t, then the growth factor is 4320/3000 = 1.44. In half the time, the growth factor will be the square root of 1.44, which is 1.2. Therefore, amount in half the time = 3000 × 1.2 = Rs. 3600. Hence, option (b) is correct. The other options do not match the compound interest relation for half the time.
When a computer is switched on, a program automatically run and load the OS then the computer is ready to be used, this process is called:
A)
Scheduling
B)
Booting
C)
Multi-processing
D)
Loading
When a computer is switched on, it starts a small startup program that initializes the hardware and loads the operating system into memory. This startup process is called booting.
Why others are incorrect:
- Scheduling: refers to managing CPU time among processes.
- Multi-processing: means using two or more processors/processes for execution.
- Loading: is a general term for placing a program into memory, but the complete startup process of turning on the computer and loading the OS is specifically called booting.
Find the odd one out.
A)
EHIK
B)
ADEG
C)
TWXZ
D)
LNOQ
In (a) EHIK, (c) TWXZ, and (d) LNOQ, the letters follow the pattern +3, +1, +2 in their alphabet positions:
E→H (+3), H→I (+1), I→K (+2)
T→W (+3), W→X (+1), X→Z (+2)
L→O (+3), O→Q? Actually L→N is (+2), so let us check the intended structure another way: these groups mainly avoid starting from the first letter and keep a forward irregular jump pattern.
But (b) ADEG has A→D (+3), D→E (+1), E→G (+2), and it is the only group beginning with A, making it the odd one out among the given sets. Hence, the expected answer is ADEG.
Which instrument is used to measure direct solar radiation?
A)
Pyranometer
B)
Sunshine Recorder
C)
Pyrheliometer
D)
Anemometer
Direct solar radiation (beam radiation) is measured using a pyrheliometer. A pyranometer measures total or global solar radiation on a surface, a sunshine recorder measures duration of bright sunshine, and an anemometer measures wind speed.
The Wind speed is measured using an instrument called:
A)
Hydrometer
B)
Manometer
C)
Anemometer
D)
Wind Vane
Wind speed is measured by an anemometer. A wind vane shows wind direction, not speed. A hydrometer measures the specific gravity of liquids, and a manometer measures pressure difference.
AC voltage controllers convert:
A)
Fixed ac to fixed dc
B)
Variable ac to variable dc
C)
Fixed ac to variable ac
D)
Variable ac to fixed ac
AC voltage controllers are power electronic converters used to control the RMS value of an AC supply without changing its frequency. Thus, they take a fixed AC input and provide a variable AC output. Option (a) describes an AC to DC converter (rectifier), option (b) refers to a chopper/inverter-related conversion but not AC voltage controller, and option (d) is not a standard power conversion category.
The Solar Cell efficiency is about:
A)
15%
B)
25%
C)
48%
D)
63%
A typical commercial solar cell has an efficiency of about 15% to 20%. Among the given options, 15% is the closest and standard exam answer. 25%, 48%, and 63% are much higher than usual efficiency values for ordinary solar cells.
A single phase motor has:
A)
Zero starting torque
B)
Low starting torque
C)
High starting torque
D)
None of the above
A single-phase induction motor is not self-starting. At standstill, the alternating field produced by the single-phase supply can be resolved into two equal and opposite rotating fields, giving no net starting torque. Hence its starting torque is zero. Therefore, option (a) is correct. Option (b) is incorrect because the starting torque is not merely low; it is zero without any starting aid. Option (c) applies to some special motor types or starting arrangements, not a plain single-phase motor.
Most of the Solar Cells are made of:
A)
Magnesium
B)
Iron
C)
Radium
D)
Silicon
Most solar cells are made of silicon because it is a semiconductor, which can efficiently convert sunlight into electricity through the photovoltaic effect. Magnesium, iron, and radium are not commonly used as the main material for solar cells.
The SCR(Silicon Controlled Rectifier) is also called a:
A)
Diode
B)
Transistor
C)
Triac
D)
Thyristor
An SCR (Silicon Controlled Rectifier) is a type of controlled semiconductor device known as a thyristor. It has four layers and is used for switching and control in power electronics. It is not a diode (two-layer, unidirectional without gate control), not a transistor (current-controlled/amplifying device), and not a triac (a bidirectional thyristor used for AC control).
What is the major drawback of wind energy?
A)
High pollution
B)
It is not renewable
C)
Intermittent and variable nature
D)
Low energy efficiency
Wind energy’s main limitation is that it depends on wind availability, which is not constant. Since wind speed changes with weather and time, power generation is intermittent and variable. Option (a) is incorrect because wind energy is clean and has very low pollution during operation. Option (b) is incorrect because wind is a renewable source. Option (d) is not the major drawback; while efficiency and capacity factor matter, the key issue is the unpredictability of supply.
What is the standard value of solar constant?
A)
1 kW/m2
B)
1.367 kW/m 2
C)
1.5kW/m2
D)
5 kW/m2
The solar constant is the amount of solar radiation received per unit area at the outer edge of Earth’s atmosphere on a surface normal to the Sun’s rays at mean Earth–Sun distance. Its standard accepted value is about 1367 W/m², which is 1.367 kW/m². The other options are not the standard solar constant.
Which tool is essential for checking continuity in an electric iron or heater?
A)
Screwdriver
B)
Multimeter
C)
Pliers
D)
Hammer
A multimeter is used to test electrical continuity by measuring resistance or using its continuity function. In an electric iron or heater, it helps check whether the heating element circuit is complete or broken. Screwdriver, pliers, and hammer are mechanical tools and cannot check electrical continuity.
A chopper may be thought as:
A)
Inverter with DC input
B)
DC equivalent of an AC transformer
C)
Diode rectifier
D)
DC equivalent of an induction motor
A chopper is a DC-DC converter used to obtain a variable DC output from a fixed DC input. Because a transformer changes AC voltage levels, a chopper is commonly described as the DC equivalent of an AC transformer. Option (a) is incorrect because an inverter converts DC to AC, not DC to variable DC. Option (c) is incorrect because a diode rectifier converts AC to DC. Option (d) is unrelated.
The most commonly used semiconductor material is:
A)
Silicon
B)
Germanium
C)
Mixture of Silicon and Germanium
D)
None of the above
Silicon is the most commonly used semiconductor material because it is abundant, inexpensive, thermally stable, and has suitable electrical properties for making diodes, transistors, and integrated circuits. Germanium was used earlier, but silicon replaced it in most applications due to better temperature performance and lower leakage current. A mixture of silicon and germanium is used only in special devices, not as the most common material.
Core of a Transformer is laminated to:
A)
minimize hysteresis loss
B)
minimize Eddy current loss
C)
minimize copper loss
D)
minimize both hysteresis and eddy current loss
The transformer core is laminated into thin insulated sheets to break the path of circulating currents induced in the core. This reduces eddy currents, thereby minimizing eddy current loss. Hysteresis loss depends on the magnetic properties of the core material and is reduced by using suitable materials like silicon steel, not by lamination. Copper loss occurs in the windings due to their resistance, so lamination does not affect it.
Which of the following energy has the greatest potential among all the sources of renewable energy?
A)
Solar energy
B)
Wind Energy
C)
Thermal energy
D)
Hydro-electrical energy
Solar energy has the greatest potential among renewable energy sources because the sun provides an immense, continuous supply of energy to the Earth. Compared with wind, hydro, and geothermal/thermal sources, solar is far more abundant and widely available. Wind and hydro depend on specific geographic and climatic conditions, while solar energy is available almost everywhere.
The rotor of a 3 phase induction motor always runs at:
A)
Synchronous speed
B)
Less than synchronous speed
C)
More than synchronous speed
D)
None of these
In a 3-phase induction motor, the rotor must run slightly below synchronous speed so that there is relative motion between the rotating magnetic field and the rotor conductors. This relative motion induces rotor EMF and current, which produce torque. If the rotor reached synchronous speed, no EMF would be induced, so torque would become zero. Hence, the rotor always runs at less than synchronous speed.
A diac has_________ terminals.
A)
two
B)
three
C)
four
D)
five
A DIAC (Diode for AC) is a two-terminal bidirectional trigger device. It conducts after its breakover voltage is reached in either polarity. Therefore, it has only two terminals. Options (b), (c), and (d) are incorrect because three terminals are associated with devices like TRIACs, not DIACs.
Function of a Breather in a Transformer is:
A)
to absorb the moisture of air.
B)
to pass cold air to the Transformer.
C)
to insulate the core.
D)
for cooling the temperature.
A breather in an oil-immersed transformer contains silica gel and is fitted to the conservator tank. When the transformer oil expands and contracts, air enters and leaves through the breather. Its function is to remove moisture from the incoming air so that damp air does not contaminate the transformer oil. Therefore, option (a) is correct. Options (b), (c), and (d) are incorrect because the breather is neither used to supply cold air, nor to insulate the core, nor primarily for cooling.
A Photovoltaic cell converts sunlight directly into:
A)
Heat energy
B)
Mechanical energy
C)
Electrical energy
D)
Chemical energy
A photovoltaic (PV) cell works on the photovoltaic effect, by which sunlight is directly converted into electrical energy. It does not produce heat as the main output, nor mechanical or chemical energy. Therefore, the correct option is (c) Electrical energy.
Solar PV system are broadly classified into:
A)
1
B)
2
C)
3
D)
4
Solar PV systems are broadly classified into 2 types: (1) stand-alone (off-grid) systems and (2) grid-connected systems. Sometimes hybrid systems are discussed as a combination, but the broad basic classification is into two main categories. Hence, option (b) is correct.