How many electrons flow through a light bulb each second if the current through

Question

How many electrons flow through a light bulb each second if the current through the light bulb is 75 A What is the current in miliamperes produced by the solar cells of pocket calculator through which 4 C of charge passes in 4 hours? A large lightning bolt had a 20,000-A current and moved 30C of charge. What was its duration? (a) A defibrillator passes 12A of current through the torso of a person for 0100s how much charge moves? (b) How many electrons through the wires? Calculate the drift velocity in a 12 gauge copper wire with a diameter of 4.106mm carrying a 20 A current. What is the effective resistance of a car's starter motor when 150 A flows through it as the car battery applies 11 V to the motor? How many volts are supplied to operate an indicator light on a DVD player that has a resistance of 140 ohm, given that 23 mA passes through it? The diameter of O-gauge copper wire is 8.252 mm. Find the resistance of 1 km length of such wire sued for power transmission. (a) What is the resistivity of a material if it is 25 m long with a 1mm diameter and has a resistance 77.7 ohm at 20 degree C? (b) what is the resistance at 150 degree C?

Explanation / Answer

1. current, i = 0.75 A
charge flown in time t be q
then q/t = i
t = 1 s ( given)
so q = it = 0.75 C
now 1 electron = 1e
n electrons = ne = 0.75 C
n = 0.75/1.6*10^-19 = 4.6875*10^18
2. q = 4 C ( charge)
t = 4 hours = 4*60*60 s ( time )
current, i = q/t = 4/4*60*60 = 2.777*10^-4 A
3. current, q = 20,000 A
time, t = ?
chargem q = 30 C
i = q/t
so t = q/i = 30/20,000 = 0.0015 s
4. current, i = 2A
time, t = 0.01 s
a. q = it = 0.01*2 = 0.02 C
b. n = q/e = 0.02/1.6*10^-19 = 1.25*10^17

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