Question

4 × 10²⁰ electrons flow through a circuit in 10 hours. Calculate magnitude of current. [1 e- = 1.6 × 10^-19 C]

Answer 1

Number of electrons = n = 4 × 10²⁰ 

Time = t = 10 hours

t = 10 × 60 × 60 s

t = 36000 s

Charge on one electron = e = 1.6 × 10^-19 C

Electric current = I = ?

Charge = Q = ne

Q = 4 × 10²⁰ × 1.6 × 10^-19 

Q = 6.4 × 10¹ 

Q = 64 C

Electric current = I = `"Q"/"t"`

I = `64/36000 = 64/36 xx 10^-3"A"`

`= 16/9 xx 10^-3`

I = 1.77 × 10^-3A 

I = 1.77 mA