Lens Formula, Magnification and Power

The video tutorial explains the characteristics of images formed by spherical lenses, focusing on the use of ray diagrams and numerical methods. It introduces the Cartesian sign convention for lenses, where distances along the direction of incident light are positive. The lens formula, 1/v - 1/u = 1/f, is discussed, applicable to both concave and convex lenses. Magnification is defined as the ratio of image height to object height, with m = -v/u. The video also covers optical power, defined as the inverse of focal length, measured in diopters. The power of convex lenses is positive, while concave lenses have negative power. The tutorial concludes with a recap of these concepts.

What is the importance of using the correct sign conventions in lens calculations?

• To ensure the lens is clean

• To arrive at the correct numerical answer

• To make the lens look bigger

• To change the color of the lens

According to the new Cartesian sign convention, what is the sign of the focal length for convex lenses?

• Zero

• Undefined

• Positive

• Negative

What is the lens formula used to relate object distance, image distance, and focal length?

• v/u = f

• v - u = f

• 1/v - 1/u = 1/f

• 1/v + 1/u = 1/f

How is magnification defined in terms of image and object heights?

• The product of image and object heights

• The ratio of image height to object height

• The difference between image and object heights

• The sum of image and object heights

What is the condition for magnification to be greater than zero?

• For real images

• For virtual images

• For erect images

• For inverted images

How is the optical power of a lens defined?

• As the square of its focal length

• As the inverse of its focal length

• As the product of its focal length

• As the sum of its focal length

What happens to the effective power when multiple lenses are used in combination?

• It becomes zero

• It is the difference of the individual powers

• It is the sum of the individual powers

• It is the product of the individual powers