Advertisements
Advertisements
Question
Calculate the total number of electrons flowing through a circuit in 20 mins and 40 s, if a current of 40 μA flows through the circuit.
[1 e– = 1.6 × 10-19 C]
Advertisements
Solution
Number of electrons = n = ?
Time = t = 20 min 40 s
t = (20 × 60 + 40) s
t = 1240 s
Electric current = I = 40 μA
I = 40 × 10-6 A
Charge on one electron = 1 e = 1.6 × 10-19 C
Charge = Q = ?
I = `"Q"/"t"`
Q = It
Q = 40 × 10-6 × 1240
Q = 49600 × 10-6 C
Q = 4.96 × 10-2 C
Now Q = n (charge on 1 electron) = ne
4.96 × 10-2 = n × 1.6 × 10-19
n = `(4.96 xx 10^-2)/(1.6xx10^-19)`
n = 3.1 × 1017 electrons
APPEARS IN
RELATED QUESTIONS
n electrons flow through a cross section of a conductor in time t. If charge on an electron is e, then write an expression for the current in the conductor.
State three factors on which the resistance of a wire depends. Explain how the resistance depends on the factors stated by you.
Name the physical quantity of which the unit is ohm
How many electrons constitute one unit electric charge in SI system?
State the relation between electric current; the number of electrons moving in a circuit and time in seconds.
Draw a diagram showing two bulbs connected in parallel to a dry cell.
