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1. ### How far apart would parallel pennies have to be to make a 1.80 pF capacitor? Estimate radius of penny to b 1cm?

yes, your equation is correct. area=(capacitance*distance)/epsilon_0 area= (pi)r^2 convert everything to meters and convert the capacitance from picoF to just F (simply multiple the given 1.80 times 10^-12) make sure you convert your final answer to...

1 Answers · Science & Mathematics · 07/01/2013

2. ### a color tv uses 120 watts pf power.how much energy does the tv use in 1 hour?

120 watts per hour is 120/ 1000 = .12 kilowatt hour. If electricity cost about 12 cents a kilowatt hour this is about 1.44 cents an hour

3 Answers · Science & Mathematics · 03/09/2009

3. ### Inductor=40 mH, Capacitor=5500 pF, resistor=50 ohms, resonant frequency=10735.66 Hz(per sec).?

Assuming the parts are in series (You should state that), and assuming the circuit is driven by a voltage source that does not change amplitude as frequency changes, then the max current is at resonance, and the reactance of the L and C...

2 Answers · Science & Mathematics · 06/12/2011

4. ### A group of small appliances on a 60 Hz system requires 20 kVA at 0.85 pf lagging when operated at 125 V (rms).?

The impedance of the line is Sqrt(0.01^2 + 0.08^2) =0.0806 ohms The current for the 20 KVA is I =20000 / 125 = 160 amps The votage drop in the line is E = I * R = 160 * 0.0806 = 12.896 volts This...

1 Answers · Science & Mathematics · 04/05/2011

5. ### bulb with 15w/6500k,lm855,pf 0.50 what z the resistance of the bulb?

You need to provide full details before this can be answered, NOT a bunch of meaningless hints. .

1 Answers · Science & Mathematics · 02/06/2011

6. ### A composite load consists of two loads connected in parallel. One draws 100 W at a PF of 0.8 lagging, another?

The power factor is 0.97 The 100 KW load at 0.8 power factor has 75 KVAR. 300 KW with 75 KVAR has 309.23 KVA. Power factor is KW / KVA or 300 / 309.23 =0.97

1 Answers · Science & Mathematics · 21/02/2011

7. ### what is power factor?what is the significance of power factor?why low pf is harmful?

All AC circuits (unless the load is purely resistive) have both resistance and reactance. We pay only for the current used by the resistive portion of the current. This part is called watts. A watt hour meter only registers...

5 Answers · Science & Mathematics · 05/10/2011

8. ### how many less windings would a transformer need if the ac was 120hz instead pf 60hz?

The winding ratio would be the same. It's dependent strictly on primary and secondary voltage requirements. You would be able to make do with a smaller iron core, though. This would reduce the overall size and weight of the transformer. However: the...

2 Answers · Science & Mathematics · 23/06/2010

9. ### correcting Power factor with capacitors?

Real power = (VA)*)pf) = (300,000VA)*(.7) = 210,000 Watts VA = (real power...real power is constant at 210kW kVARs at a .8 pf = (tan arc cos .8)*(210kW) = 157.5kVAR kVARs...

2 Answers · Science & Mathematics · 30/09/2011

10. ### Determine the capacitance of the following?

just guessing: 33000 pF or 33 nF 100000 pF or 100 mF or 0.1 µF 4700...

1 Answers · Science & Mathematics · 03/12/2010