Wave Applications - Lenses

Question 1

Optical Centre

Answer 1

A point in the lens through which rays will pass without deviation

Question 2

Principle Axis

Answer 2

A line that passes normally (at 90°) through the optical centre of the lens

Question 3

Focal Length (f)

Answer 3

Displacement along the principle axis from the optical centre of a lens to the real/virtual focal point

Question 4

Power of a Lens (Ρ)

Answer 4

Power = 1/focal length (measured in dioptres, m^-1)

Question 5

Converging Lens

Answer 5

Parallel rays pass through the lens and converge to meet at a real focal point (has a positive power and focal length)

Question 6

Diverging Lens

Answer 6

Parallel rays pass through the lens and diverge from a virtual focal point (has a negative power and focal length)

Question 7

The Lens Equation

Answer 7

1/u + 1/v = 1/f (where u = distance parallel to the principle axis from the object to the optical centre and v = the distance parallel to the principle axis from the optical centre to the image)