Ch 25: The Electric Potential

Knight Calc - Physics for Scientists and Engineers 5th Edition

Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796당신이 사용하는 게 아니라요?교과서 변경

Knight Calc 5th Edition

Ch 25: The Electric Potential

문제 29b

25장, 문제 29b

In a semiclassical model of the hydrogen atom, the electron orbits the proton at a distance of 0.053 nm. What is the electron's potential energy?

검증된 단계별 안내

Step 1: Recall the formula for the potential energy of a system of two charges. The potential energy (U) is given by the equation:

U = \frac{-}{k q q_{1} q_{2}}

, where

k

is Coulomb's constant,

q q_{1}

and

q_{2}

are the charges of the proton and electron, and

r

is the distance between them.

Step 2: Identify the values of the constants and variables. The charge of the electron and proton is

q = - 1.6 \times 10^{- 19}

C and

q = 1.6 \times 10^{- 19}

C, respectively. Coulomb's constant is

k = 8.99 \times 10^{9}

N·m²/C². The distance

r

is given as

0.053 n m

, which needs to be converted to meters:

0.053 \times 10^{- 9}

Step 3: Substitute the known values into the formula. Replace

k

q_{1}

q_{2}

, and

r

into the equation:

U = \frac{-}{8.99 \times 10^{9} \times (- 1.6 \times 10^{- 19}) \times (1.6 \times 10^{- 19})}

Step 4: Simplify the numerator. Multiply the constants and charges in the numerator:

(8.99 \times 10^{9}) \times (- 1.6 \times 10^{- 19}) \times (1.6 \times 10^{- 19})

. This will yield a negative value because the charges are opposite in sign.

Step 5: Divide the result of the numerator by the denominator. Use the value of

r

in meters to complete the calculation. The final result will give the potential energy in joules (J).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Coulomb's Law

Coulomb's Law describes the electrostatic force between two charged particles. In the case of the hydrogen atom, it explains the attractive force between the negatively charged electron and the positively charged proton. The potential energy associated with this force can be calculated using the formula U = -k * (e^2 / r), where k is Coulomb's constant, e is the charge of the electron, and r is the distance between the charges.

Potential Energy in Electric Fields

In the context of electric fields, potential energy represents the work done to move a charge from a reference point to a specific point in the field. For the hydrogen atom, the potential energy of the electron is negative, indicating that work must be done against the electric force to separate the electron from the proton. This negative value reflects the stability of the electron's orbit around the proton.

Quantum Mechanics and Energy Levels

Quantum mechanics introduces the concept of quantized energy levels for electrons in atoms. While the semiclassical model approximates the electron's orbit, it is important to recognize that in reality, electrons exist in probabilistic clouds rather than fixed orbits. The potential energy calculated in this model is a simplification, but it provides insight into the energy interactions within the atom, which are foundational for understanding atomic structure.