Question

You pull your t-shirt out of the washing machine and note that 1532 particles have become attached, each of which could be either an electron or a proton. Your t-shirt has a net charge of −2.94 10-17 C.

(a) How many electrons are attached to your t-shirt?

___________electrons

(b) What is the mass of the particles attached to your t-shirt?

____________kg

Answer 1

As we know that the elementary charge is 1.6×10^-19 C

Now, the net charge on the t - shirt = q = -2.94 x 10^-17 C

Negative sign inducates that the electrons are surplus on the t-shirt.

So, we have -

2.94×10^-17/ (1.6×10^-19) = 184 electrons surplus

(a) Total number of electrons in the t-shirt = 1532/2 + 184/2 = 858

(b) Total number of protons = 1532/2 - 184/2 = 674

So, mass of the particles attached to the t-shirt = 858 x 9.11×10^-31 + 674 x 1.67×10^-27

= 7816.38 x 10^-31 +  1125.58 x 10^-27

= 0.781638 x 10^-27 + 1125.58 x 10^-27

= 1126.4 x 10^-27 kg = 1.126 x 10^-24 kg.