Electronics FAQ – Your Multilingual Guide to Electronics

  How to Wire 2-Way Switches to Control One Light Fixture | 2-Way Switch Wiring Diagram, Steps, and Connection Guide What is a two-way switch? You need ‘ Two Way ’ and not ‘three way’ as wrongly mentioned in the earlier answer. The technical name of the switch is   SPDT,   i.e. ‘ S ingle   P ole   D ouble   T hrow ’ switch. Uses of a Two-Way switch:  Staircase light control:  A two-way switch is used for the staircase light control from the two different locations.  Wiring diagram of Two-Way switches:  The most popular application of this switch is ‘Staircase light control’ and ‘Bed switch’. Wiring and function are shown in the following animation. Animation of the working of a Two-Way switch: Wiring diagram of Two-Way Switches:  FAQ Set: Q1. What is a two-way switch wiring system? A two-way switch system allows a single light fixture to be controlled from two different locations using two switches. Q2. Where is a two-switch light c...

  Which Is More Economical — 110V vs 220V Power | Energy Efficiency, Electricity Cost, and Home Wiring Cost Comparison Some country uses 220V, whereas some use 110V. Which electrical system is economical to use? Power is the Product of Voltage and current: Although voltage is important for calculating power, we also need to consider load current to calculate power. The product of voltage by current gives power. If power remains constant, decreasing the voltage requires an increase in current to maintain the same power. Hence, the operating cost, i.e. electricity bill, won't change. Now let’s come back to OP’s question. Which one is more economical? What about installation cost? A 230V installation would be more economical. Why? We need to calculate the installation plus operating cost. Because of the lower current in a 230V circuit for the same power, economically thinner wires can be used, which saves on installation costs, although the operating cost remains the same. FAQ Set: Q1...

Can the Energy Stored in an Inductor Be Used Practically? Applications, Benefits, and Real-World Examples. Why does an inductive load create sparking across contacts?  An inductor stores energy in the form of a magnetic field as long as current is flowing through it. As the current stops, the magnetic field began to collapse. Collapsing magnetic flux is also a rate of change of magnetic flux that will induce a large voltage spike (back EMF) across it. Energy stored in an Inductor:  Since this induced voltage is parallel to the inductor coil, it decays by converting it to heat across the coil resistance. During this process, the coil generates a magnetic field again due to the flow of decaying current through the coil, which results in electromagnetic interference during radio operation and sparking across open contacts. Adverse effects of stored energy in an inductor:  Can we put this back-EMF into use? Yes. Practical Use of Stored Energy in an Inductor:  Spark-ignit...

Electrical Earthing Tests – Importance, Types, Procedures, Safety Standards, and Best Practices Explained. Easy method to test home earthing. An instrument that measures ground (earth) resistance: If you're paranoid about the effectiveness of the earthing, then you need three three-wire earthing tester. There is a procedure for that. You may also call a third-party agency that certifies electrical earthing. But, is there an easy, inexpensive method? Yes. It is crude, but it gets the job done. Method-1 (Using filament lamp) Take a 100W filament bulb with a holder. First test it across the phase and neutral of the home electrical plug. Note the brightness. Then connect the bulb to the Earth and the Phase of the plug. Note the brightness. If the electrical earthing is good, you will have equal brightness in both cases. Why bulb lights with Earth-Phase connection? I have explained it   here. Method-2 (Using Digital Multimeter) You need a DMM.   Measure the voltage difference betwe...

Why Does AC Current Reverse Direction Periodically? Understanding Alternating Current generation, Frequency, and Working Principle of an AC generator The answer to this question goes back to the generator where AC power is generated. A simple voltage generator:  Imagine a simple loop of coil is rotating between the two strong magnetic bars. 0 to 180 degrees,i.e. Half rotation. You will notice that when the coil is perpendicular to the magnetic field, its output is minimum or zero due to the minimum linkage of the magnetic field. But as the coil rotates to become parallel to the magnetic field, its output increases and becomes maximum when it is parallel. 180 to 360 degrees, i.e. Full rotation. The same cycle repeats, but now the voltage is negative. The following diagram explains it. Hence, as the AC voltage reverses its polarity periodically, the load current will also change direction of flow periodically. AC current direction: FAQ Set: Q1: Why does AC current reverse direction p...

Importance of correct Working Voltage for a Relay – Why it affects Function and Safety?  Relay various parts and their functions. Relay animation.  Let's see how relay functions: Parts of a typical relay: As you can see from the above animation, the coil must develop sufficient magnetic strength to overcome the spring tension of the armature that operates the contacts. At 12V, the coil may not develop that magnetic strength. Relay might operate, but not reliably. Also, weak spring relay contact pressure may lead to sparking and could damage it. FAQ Set: Q1: Why is the correct working voltage important for a relay? The relay’s coil is designed for a specific voltage. Applying   too low a voltage   may prevent it from activating, while   too high a voltage   can overheat or damage the coil, affecting both function and safety. Q2: How does incorrect voltage affect relay operation? Low voltage:   Coil may not generate enough magnetic force to close contact...

Why Is Transformer Rating Given in VA? Understanding Power in Volt-Ampere versus watts, Power Factor, and Transformer Efficiency related to inductive load Real reason: Because the manufacturer of the transformer never knows where it is going to be used. Suppose a transformer of 100KVA feeds a resistive load; it will develop 100 kilowatts of power across the load because the power factor of the resistive load is unity. If the same transformer feeds an inductive load of power factor 0.5, then it will develop only 50 kilowatts of power across the load. Hence, if I want to rate a transformer in watts, then I need to know the power factor of the load, which is impossible. So, the transformer is rated in VA, KVA or MVA. A mug of beer analogy of Power Factor: FAQ Set: Q1: Why is transformer rating given in VA instead of watts? Transformer ratings are given in   VA (volt-amperes)   because transformers must handle   apparent power , which includes both real power (watts) and reac...

Why Do some Batteries Connected in Series Heat Up? Causes, Safety Risks, and Prevention Tips. Internal resistance of the battery is explained.  To understand this, let’s solve a quiz.   Higher resistance dissipates more power in a series circuit: Two lamps. 40W and 100W are connected in series. Which one will give more light? Popular to the misbelief that having more wattage, 100W, will give more light.   No, exactly apposite, 40W will give more light. Why? Because a 40W bulb has more filament resistance than a 100W bulb. In a series circuit, the current remains constant, so the I^2 x R product, i.e., heat, is greater for a 40W lamp than for a 100W lamp, hence producing more light. Batteries are connected in series for the Inverter and UPS:  Why all this rant? Because batteries are commonly connected in series, especially in UPS systems. Every battery has an Internal resistance:  Why do some batteries have more internal resistance? It depends on the age of the b...

Why Does Sparking Occur Across a Switch When Switching Inductive Loads? Causes, Effects, and Protection Methods. Effect of Back-EMF explained. A circuit breaker or switch that controls an inductive load has a spark across the contacts when they physically separate. Sparking across the contact that controls the inductive load: The reason is that when the switch becomes off, a falling magnetic field across the inductive load generates a high voltage pulse of back EMF that ionises the air the moment contact physically separates with a loud pop. Why, because ionised air temperature can be up to 4000 K. That temperature creates a violent expansion of the air that is heard as a pop. This ionisation of the air is nothing but plasma (arc) that can conduct current through the air. It appears as a bright spark with pop, especially in a dark environment. How to reduce sparking across the contact? A snubber circuit parallel to the contact can reduce sparking.  Lightning is nothing but the ioni...