Another unit of charge is the electrostatic unit (esu). It is defined as follows: Two point charges, each of 1 esu and separated by \(1 \mathrm{~cm}\), exert a force of exactly 1 dyne on each other: 1 dyne \(=1 \mathrm{~g} \mathrm{~cm} / \mathrm{s}^{2}=1 \cdot 10^{-5} \mathrm{~N}\). a) Determine the relationship between the esu and the coulomb. b) Determine the relationship between the esu and the elementarv charoe

Short Answer

Expert verified
Answer: (a) 1 esu is approximately equal to 3.34 x 10^-10 C, and (b) 1 esu is approximately equal to 4.8 x 10^-10 elementary charges.

Step by step solution

01

(Step 1: Recalling the definition of esu)

An electrostatic unit (esu) is defined as a unit of charge such that two point charges, each of 1 esu and separated by 1 cm, exert a force of exactly 1 dyne on each other. Additionally, 1 dyne is equal to \(1\times 10^{-5}\) N.
02

(Step 2: Using Coulomb's law)

Coulomb's law states that the electrostatic force (F) between two charged particles is given by: $$ F = k {\frac{q_1 \cdot q_2}{r^2}} $$ Where \(k\) is Coulomb's constant (\(8.99 \times 10^{9} \dfrac{Nm^2}{C^2}\)), \(q_1\) and \(q_2\) are the respective charges, and \(r\) is the distance between the charges. For our case, the given force (\(F_{esu}\)) is 1 dyne (\(1\times 10^{-5}\) N), \(q_1=q_2=1 \text{ esu}\), and \(r=1 \text{ cm}=0.01 \text{ m}\).
03

(Step 3: Solve for the relationship between esu and coulomb)

Now we plug the values into Coulomb's law formula to find the relationship between esu and coulomb. $$1\times 10^{-5} \mathrm{N} = k \frac{(1 \text{ esu})^2}{(0.01)^2} $$ Solving for esu: $$ 1 \text{ esu} = \sqrt{\frac{1\times 10^{-5} \mathrm{N} \cdot (0.01)^2}{k}} $$ Plug in the value of \(k\) to get the conversion factor between esu and coulomb: $$ 1 \text{ esu} = \sqrt{\frac{1\times 10^{-5} \mathrm{N} \cdot (0.01)^2}{8.99 \times 10^{9} \dfrac{Nm^2}{C^2}}} $$ Calculating this, we get: $$ 1 \text{ esu} \approx 3.34\times 10^{-10} \text{ C}$$
04

(Step 4: Determine the relationship between esu and elementary charge)

We know that the elementary charge (\(e\)) is equal to \(1.6 \times 10^{-19} \text{ C}\). To find the relationship between esu and the elementary charge, we will divide the elementary charge by the conversion factor found in Step 3: $$ \frac{e}{1 \text{ esu}} = \frac{1.6 \times 10^{-19} \text{ C}}{3.34\times 10^{-10} \text{ C}} $$ Calculating this, we get: $$ \frac{e}{1 \text{ esu}} \approx 4.8\times 10^{-10} $$ So, the relationship between the esu and the elementary charge is: $$ 1 \text{ esu} \approx 4.8\times 10^{-10} \text{ elementary charges} $$

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