Solve the given problem:
 
Define power of a lens. The focal length of a lens is \(-7\ cm\). Write the nature of the lens and find its power. If an object is placed at a distance of \(24\ cm\) from the optical centre of this lens, according to the New Cartesian Sign Convention, what will be the sign of magnification in this case ?
 
A lens's power is equal to the . It is denoted by the letter . The SI unit of power is . The power of a lens is calculated as follows:
 
P=1i
 
The nature of lens is .
 
The power of lens is \(D\).
 
The sign of the magnification is .
 
Important!
Note: Enetr your answer with 3 decimal digits.