The Books definition of financial leverage is " The use of debt in a firm's capital structure is called financial leverage .

The Books definition of financial leverage is " The use of debt in a firm's capital structure is called financial leverage. The more debt a firm has (as a percentage of assets), the greater is its degree of financial leverage" p 25. (Ross, 2014)

the name of the book: Essentials of Corporate Finance, 8th Edition

point out the impact and risk of financial leverage? 

Give the reference