The Current in an Electron Beam in a Cathode-Ray Tube

question 20

Multiple Choice

The current in an electron beam in a cathode-ray tube is measured to be 50 µA.How many electrons hit the screen in 4.0 s? (e = 1.6 × 10−¹⁹ C)

• A) 2.5 × 10¹¹ electrons
• B) 2 × 10¹³ electrons
• C) 1.2 × 10¹⁵ electrons
• D) 3.1× 10¹⁸ electrons
• E) 1.6 × 10¹⁷ electrons

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Definitions:

Long-Run Equilibrium

A state in which all inputs and outputs in a market are fully adjusted and there is no tendency for change, often associated with perfect competition markets.

Marginal Revenue

The extra revenue obtained by selling an additional unit of a product or service.

Marginal Cost

The cost increase from producing a further unit of a product or service.

Long-Run Equilibrium

Long-run equilibrium occurs in a market when all firms earn normal profits, and no new firms have an incentive to enter or exit, resulting in market stability over time.