Electronics Engineering

Whenever a charge passes through a conductor, a magnetic field is produced. Hence, whenever a current carrying conductor is placed in a magnetic filed, it will experience a force whose direction is determined by Fleming's left hand rule.

Yes, the output current of a 40va transformer at 12 volts is 3.33 amps. The replaced unit had an output of 1 amp making it a 12va transformer. By doing this exchange there will be three times the capacity of the new transformer over the old transformer.

These convert pressure into voltage. When certain crystals are compressed or stretched, they exhibit a voltage across their faces, which can be utilised for various applications. The simplest example is an inexpensive 'crystal' phonocartridge: when the attached stylus vibrates in the grooves of a record, the crystal creates variations in voltage which can be amplified using an amplifier which then produces sound via a loudspeaker.

These crystals also work the other way around, compressing or expanding when voltages are applied across their faces. This is the principle behind, for example, ultrasonic cleaners -high-frequency voltages applied across the crystal results in ultrasonic vibrations.

Work it out yourself -the equation is: voltage = current x resistance.

Power is volts times amperes, so 120 V and 50 A would be 6000 watts.

However, it also depends on phase angle and power factor, something that is related to reactive loads such as motors and power supplies. As a result, the power may actually be less, so it is more correct to say 6000 volt-amps. The case of 6000 watts being the same as 6000 volt-amps is only true for a purely resistive load such as a toaster.

An amplifier generally amplifies an AC waveform (such as sound), and is powered by a DC source. The majority of the power at the output is then coming from a DC source (the power supply in a power amplifier will convert the 50/60Hz AC power in to DC for the amplifier circuitry). So you can make the argument the above (question) is a true statement.

But an amplifier wouldn't be used to convert from DC to AC power (in general).

The resistors should be connected in parallel .

"WI FI" is a neologism (new word) that represents a play on the old slang "Hi Fi", which originally meant "high fidelity" (music) and was generally applied to phonographs and the vinyl records played on them. "WI FI" would therefore be "wireless high fidelity", consisting of broadband wireless routers used privately or publicly to connect computers at high speed.

The only type I am familiar with is the Bird 4391M. This a a digital display wattmeter whereas the Bird 43 is an analog (mechanical meter) device. The digital wattmeter has many functions available such as FWD PWR, RFL PWR, MOD, that are selected by front panel push buttons. It is a very versatile unit for measuring RF signal power. The one disadvantage to the digital wattmeter is that it needs to be powered to operate, either on AC line or the rechargeable battery pack. The Bird 43 wattmeter is a very simple unit to operate and requires no external power. You simply plug in the correct element, making sure the arrow on the element points in the same direction as the RF signal flow, apply the RF power and get the meter reading. With both types of wattmeters, the frequency and power range desired to be measured is determined by plug-in elements that go into the front panel of the unit. If using a Bird wattmeter, I would suggest using Bird elements. The ones made by Coaxial Dynamics are good, but the can sometimes cause calibration errors. I have calibrated the Bird wattmeters for many years and they are very durable. You may want to do an internet search on Bird wattmeters for more information on their particular functions. Hope this helps.

In regards to the capacity of a conductor, the rating is in amperage. Voltage is an insulation factor which refers to the amount of voltage that can be applied to an insulated conductor before the insulation breaks down. A break down of insulation is the main factor of creating a short circuit condition.

Back emf in a DC Motor plays a role of a regulator,We know the basic equation V=IaRa+Eb,where Ia,Ra are is the current through and resistance of the armature coil,Eb is the back emf and V is the Pd applied.Consider,

Ia=V-Eb/Ra,The value of Ra is really small, just a few ohms and V would generally be around 240-220V(Indian conditions),assuming Eb to be zero(at the time of starting),it shows that Ia comes to be a really large value that the motor coil can barely handle,thats why we use a 3,2 POINT Starter that avoids large starting current,Now in the running condition of the motor Back emf would naturally be produced(say around 200V) this tends to reduce the value of(V-Eb), thus stopping a large current from entering the coil.But as the Load applied to the motor increases , Back emf would naturally come down to allow more current to enter the coil upto its rated value,to deliver the load requirement.thus Eb acts as a regulator.(Eb opposes the applied voltage)

Those Green color are called soldermask.They are available in many colors including Green & black.

The purpose is to protect the Cu layer from corrosion and provide good insulation.

Voltage is current times resistance, 1.2 x 110 = 132 volts.

Wire is sized to carry current, it doesn't matter whether the voltage is AC or DC. The larger the diameter of the wire the more current it is allowed to carry.

NOT Possible. In a parallel combination the power tollerence has to increase, thus for every additional resistor in parallel the effective power capacity of the resister would be n(12) Watts where n is the number of resistors connected. ie. if n=3 the power of the combination would rise to 12 x 3 = 36W. Also it is not possible to compute the effective resistance of the combination unless the resitance value of the resitors utilised is known. The question is therefore invalid.

many digital electronics require some notion of time passing to operate. For example a time of day clock requires a signal of one second to update the time signal which is basically just a special counter. An oscilloscope needs some time reference to advance the trace across the X-axis of the screen. A frequency counter literally measures events during a given time interval.

In these instruments, there will be a signal called a clock which is basically an oscillator-driven signal which is processed to a digital signal called a "clock" and used to measure or advance events every clock cycle.

Usually the time base clock is the major factor determining the overall accuracy of the instrument so better instruments have clocks derived from crystal oscillators and variations of crystal oscillators with even better characteristics.

the disadvantages are that over a period of time gate valves seize and become in operable. also the handles of gate valves corrode quickly and gate valves don't entirely close properly making it difficult to solder. Gate valves are used for positive shut off and Gate valves are not designed for throttling like a globe pattern type . Gate valve fail because the installer has no idea what these types of valves are intended to do such as main steam shut off's or water mains..If properly used and installed correctly these valves last over 100 years under extream conditions

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It helps historians to remember to check other sources for facts.

in ac circuits

power,P=VICOS@

@ is the angle between voltage and current.

in dc

P=VI

V is the voltage

I is the current.

Power (in Watts) is current (A) x voltage (V)

Overgeneralization (A+)

The numerical representation of one coulomb of charge moving past a point in a circuit per second is called an ampere.