Question

A body has a charge of -2 micro coulomb if it has 2.5*10^13 protons, then how many electrons the body has

please answer fast
im going to have an exam in 10 min

Answer 1

The solution is in the attachment.

Answer 2

Concept:

According to the Quantization of charge, the Charge on the body is always quantized.

The total charge on the body is equal to the total charge due to protons and the charge due to electrons.

Given:

Charge, q = -2μC = -2×10⁻⁶ C

Number of protons, p = 2.5 ×10¹³

Find:

The number of electrons.

Solution:

According to the Quantization of charge,

q = -ne + pe

where n and p are the numbers of electrons and the number of protons respectively.

Charge on one electron, e =  1.6 ×10⁻¹⁹ C

q = -ne + pe = e (-n+p)

-2×10⁻⁶ C =  1.6 ×10⁻¹⁹ C (-n + 2.5 ×10¹³ )

-1.25 ×10¹³ = -n + 2.5 ×10¹³

n =  2.5 ×10¹³ + 1.25 ×10¹³ = 3.75 × 10¹³

Hence, the number of electrons in the body is 3.75 × 10¹³.

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