Electrical Engineering

All transformers are magnetic. A transformer is two (or more) coils of wire wound together. The varying magnetic field created by the primary winding induces a current in the secondary coils proportional to the ratio of the number of turns. You're probably refering to a switchmode powersupply as a "electronic transformer" (which is bad nomenclature, by the way). A switch mode supply actually contains a normal transformer in its core, along with circuitry to allow for a wide input fange and a narrow output range.

Because differences in temperature cause the materials to either shrink or expand. With a lot of shrinking and expanding occurring, these materials would crack or break down if there wasn't any allowance for the movement. Also these gaps are used to compensate for the weight of the load crossing vehicles which presses the bridge to its maximum shear capacity. The gaps serve as this allowance for movement in terms of both temperature and weight.

Many railway tracks no longer make use of these gaps as they are pre-tensioned and then placed into position in this "stretched" form. Thus, as temperature rises, the tension in the tracks decreases, but the material does not buckle, since it is already stretched!!!

Using it at a voltage higher than the one specified is one way to make a capacitor fail.

A: elevated temperature and cycling on-off power will cause capacitors to fail by beginning to leak.

Electric Source

You hook both to an electric Load.

It never referred as ratio but Rather a gain A in the form of output divided by the input and implies voltage A=gain. basically is input resistance divided by the feedback resistance

I recently installed a small fridge in the back of my van and wondered what was the best way to connect it up as I didn't want to end up with a flat engine battery.

Having Googled the subject I found a site that sells what is known as a 'split charge relay'. I emailed the firm (www.brocott.co.uk) who explained how it worked. The 'voltage sensing relay' is connected between the main engine battery and a second (leisure) battery that I have since installed in the back of the van. When the engine is running, the voltage sensing relay allows charge through to the second battery, via the main battery but only as much as is required, then it switches off. It monitors the battery voltages and allows charge through when needed.

The nice thing about this relay is that once the engine is switched off, the 2 batteries are isolated so there is no chance of getting a flat main battery. Furthermore, the installation of the voltage sensing relay is quite straight forward and you DON'T have to mess about with alternator connections or ignition wires, so very simple indeed. Now I can run any additional appliances from the leisure battery and not worry about a flat...

A coil of wire wrapped around an iron core forms an inductor. In AC systems, an inductor's impedance appears equivalent to j*w*L (j = i = imaginary number, w = omega = frequency in radians, L = inductance).

A surge is inherently high frequency. Here's an example to help explain why this acts as a surge supressor:

Say I have a 10mH surge supressing inductor. My device uses 1 amp of current at 120 volts, so its' resistance is 120 ohms. Under normal operation (60 Hz), the inductor's impedance appears as (j*2*pi*60*10/1,000) 3.8 ohms. Voltage to my device is ~120 volts, and voltage dropped (or "supressed") is (3.8 / (120 + 3.8) * 120 ) = 3.7 volts. My device is only seeing 116.3 volts with this inductor in place, but that's not enough of a dip to hurt its' operation.

A power surge hits this device. This power surge is at a frequency of 50kHz, and a voltage of 80v (an overvoltage to my device of 120 + 80 = 200 volts). The impedance of the inductor "looks like" (j*pi*50,000*10/1,000) 3141 ohms, which is in series with my 120 ohm load. The surge voltage dropped across the inductor is (3141 / (3141+120) * 80) = 77 volts, so my device gets hit with ~3 surge volts (total voltage = 60 Hz voltage of 116.3 + 50kHz voltage of 3 = 119.3 volts).

If when u put ur finger on it it's so hot that u can't keep your finger on it turn he car off. If the car is water proof u may pour water on it to prevent further over heating. If not you may wanta start cleaning the car more specifically around the motor to prevent dirt build up in the motor and this may stop overheating

if it is an A.C supply we can amplify by transformers, transistors, voltage doublers and voltage multipliers.

but if it is an D.C supply, the voltage can be amplified only by means of choppers (i.e buck converters, boost converters and buck boost converters)

The wire used in the armature windings will be a different length and thickness, suitable for the voltage used and the power required.

You can buy an "inverter." It plugs into the cigarette lighter or accessory plug or directly clips to the battery terminals and converts the 12 volt DC to AC. You can then plug your appliance into it. Be sure to get an inverter that is the right wattage capacity for your device.

acculy,i want to know that the ranking position of ibais university in bangladesh

Ingress Protection

IP 44

First Index Number - Foreign Bodies Protection, Solids

Tools and wires etc with a thickness >1mm, Granular foreign bodies, diam. >1mm

Second Index Number - Water Protection, Liquids

Spray water from all directions, (limited ingress permitted), Splashing

depends on the simple circuit. please describe it.

A solid state relay (SSR) is an electronic device to switch the electrical current, rather than an electromechanical device.

An electromechanical relay uses a magnetic coil and mechanical contacts. When current flows through the coil, it pulls down a piece of iron called an armature, causing the mechanical contacts to touch and thus close an electrical circuit.

A solid state relay (SSR) has no mechanical moving parts, but instead uses a three terminal device such as a triac (triode AC), SCRs (back-to-back thyristors), or FET (field effect transistor) to conduct the electrical current. When the third terminal (gate) is energized by the control input, the device conducts.

Essentially the solid state relay controls a larger electrical current by accepting a small control signal. There are no moving parts.

Advantages of solid state relays are: they have no internal arcing or contacts to wear out, can last virtually forever, can have extremely low control input requirements, and are immune to vibration or G-force chatter.

There are 3 installation parameters that must be planned for. Avoid over-amperage (inrush > than SSR rating), over-voltage (voltage surges) and over temperature. Solid state relay has also opto isolation feature. control signal & power line is completely isolated by an internal LED. It is just like a big version of Opto Coupler.

Mechanical Engineer

Hydrometer

The ability of an organism, or part of an organism, to detect changes in the environment is termed as sensitivity.

What is microphone sensitivity?

A microphone sensitivity specification tells how much electrical output in millivolts a microphone produces for a certain sound pressure input in dB SPL. If two microphones are subject to the same sound pressure level and one puts out a stronger signal (higher voltage), that microphone is said to have higher sensitivity.

It is important to store electrical energy just as it is important to store any type of energy. Stored energy can be used as opposed to wasting it and therefore fewer resources are needed to generate new energy. Storing Electrical Energy is not as obvious as you would think. Batteries are one way to store it, but this requires a lot a space, and resources to install, & maintain. Batteries have a limited amount of storage capability. Some industries will pump large amounts of water to large storage tanks during off-peak hours* and then release this water to power hydro generating systems to produce electricity for peak* production hours. Some types of Solar generation will use the sunlight to heat tubes of oil. The heated oil is then transferred to a typical steam turbine generator. This process can only run actively when there is sunlight present. The heated water can be stored for short periods of time for use when sunlight isn't present or additional demand is needed. *Peak: Usually during the day when the demand for electricity is at its highest. Power Co.'s will charge industrial customers more for electricity during these periods. -Don't forget to recommend Kevlarster if you like this answer!

You need to match the speaker with the amplifier. Better or worse is not the question. The question is dynamic range and the possibility of overloading the amplifier. If the amplifier is rated 4 ohms, use a 4 ohm speaker. Same for 8 ohms. Do not "mix and match".

an incomplete circuit

The outlets in your house are in parallel with each other. If your question is is your TV in series with something else plugged into your house, it is not, it is in parallel (since your house wiring is in parallel).

The giveaway for series or parallel circuits is if you remove one element in a series circuit, you will kill all other elements. In a parallel circuit, there shouldn't be a noticeable difference.

For example, if you have a surge protector plugged into your wall, and a lamp plugged into your wall, and your TV and DVD player are plugged into the surge protector:

The surge protector is in SERIES with your TV and DVD player

The surge protector is in PARALLEL with your lamp

The DVD player and TV are in PARALLEL

providing mission essential power

Look up "op amp" on wikipedia, there is a good drawing near the bottom right. An op amp contains a differential amplifier as the first stage, but has multiple following stages that provide amplifier near ideal characteristics of high input resistance and low output resistance (it can drive more current than a single dif amplifier stage).