Question

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Answer 1

Solution :-

Number of electron = n = ?

Time = t = 20 min 40s

t = (20×60+40)s

t = 1240 s

Electric current = I = 40 uA

I = 40 × 10-⁶

Charge on one electron = 1 e = 1.5 × 10-¹⁹ C

charge = Q = ?

I = Q/t

therefore, Q = It

Q = 40 × 10-⁶ × 1240

Q = 49600 × 10-⁶C

Q = 4.96 × 10-² C

Now , Q = n (charge on 1 electron ) = ne

4.96 × 10-² = n × 1.6 × 10-¹⁹

=> 4.96 × 10-² / 1.6 × 10-¹⁹

n = 3.1 × 10 ¹⁷ electrons.

Answer :- 3.1 × 10¹⁷ electrons.

Answer 2

Solution:-

Let,

• the number of electron be n.

⠀

Now,

→ Time = t = 20 min 40s

→ t = (20 × 60 + 40)s

→ t = 1240 s

⠀

Then,

→ Electric current = I = 40 uA

→ I = 40 × 10 -⁶

⠀

→ Charge on one electron = 1 e = 1.5 × 10 -¹⁹ C

→ charge = Q = ?

→ I = Q/t

⠀

→ Q = It

→ Q = 40 × 10 -⁶ × 1240

→ Q = 49600 × 10 -⁶C

→ Q = 4.96 × 10 -² C

⠀

→ Q = n = ne

→ 4.96 × 10 -² = n × 1.6 × 10 -¹⁹

→ 4.96 × 10 -² / 1.6 × 10 -¹⁹

→ n = 3.1 × 10 ¹⁷

⠀

Hence,

• number of electrons are n = 3.1 × 10 ¹⁷