Think you have what it takes to manage the electrical complexities of a fast-paced site? We’ve put together a series of targeted questions designed to challenge your understanding of real-world electrical systems. These aren’t your standard university questions; these are the scenarios you face on the floor. Dive into the challenge below and see how your practical instincts measure up!
Question 71
Electrical battery is a device that
(a) Generate EMF by chemical action
(b) Converts mechanical energy into electrical energy
(c) Converts heat energy into electrical energy
(d) Converts sound energy into electrical energy
The correct answer is (a) Generate EMF by chemical action
Question 72
Static electricity is produced by
(a) Chemical reaction
(b) Friction
(c) Induction
(d) Friction and induction
The correct answer is (b) Friction
Question 73
An Electromagnet/ Permanent Magnet can be made by
(a) Single touch method
(b) Double touch method
(c) Divided touch method
(d) Passing current through solenoid
The correct answer is (b) Double touch method
The Secret is in the “Magnetic Domains”
Inside ferromagnetic materials (like iron, steel, or cobalt), there are microscopic regions called magnetic domains. Think of these domains as tiny, individual compass needles packed inside the metal.
- Unmagnetized State: In a regular, unmagnetized steel bar, these tiny “needles” point in completely random directions. Their individual magnetic forces pull against one another and cancel each other out, so the bar as a whole has no overall magnetic field.
- The Double Touch Process: When you place the North pole of one magnet and the South pole of another in the center of the bar and drag them outward, their strong, external magnetic fields pull on those tiny internal domains.
- Alignment: The physical stroking motion acts like a comb, forcing those randomized domains to rotate and align uniformly in the same direction.
- Permanent Magnetization: Once enough of these domains are locked into this aligned formation, their individual magnetic forces combine into one large, unified magnetic field. The steel bar is now a permanent magnet!
Why “Double” Touch?
There is also a “single touch” method—which involves stroking the metal with just one magnet from one end to the other in a loop—but the double touch method is generally preferred.
Question 74
Normal frequency adopted for AC generation in our country is
(a) 60 Hz
(b) 25 Hz
(c) 30 Hz
(d) 50 Hz
The correct answer is (d) 50 Hz
Question 75
The frequency of the machine depends upon
(a) Pair of poles
(b) Angular velocity
(c) Nature of supply
(d) Rating of the machine
The correct answer is (a) Pair of poles
Question 76
The angle between voltage and current is called
(a) Form factor
(b) Power factor
(c) Phase difference
(d) Peak factor
The correct answer is (b) Power Factor
Question 77
The power factor of a purely resistive circuit is
(a) Leading
(b) Zero
(c) Lagging
(d) Unity
The correct answer is (d) Unity
Question 78
The meter used for electrical power is called
(a) KWh meter
(b) Voltmeter
(c) Ammeter
(d) Wattmeter
The correct answer is (d) Wattmeter
Question 79
The meter used for measuring potential difference of a circuit is called
(a) Ohm meter
(b) Voltmeter
(c) Ammeter
(d) Energy meter
The correct answer is (b) Voltmeter
Question 80
In case of three phase supply, the electrical displacement of the winding is
(a) 180°
(b) 90°
(c) 120°
(d) 60°
The correct answer is (c) 120°