NSAA NSAA Physics - Waves and Optics 3

Question 1

A convex lens of focal length 20 cm forms a real image of an object 60 cm away. How far from the lens is the image?

Accepted Answer

30 cm

Answer

15 cm

Answer

20 cm

Answer

40 cm

Question 2

What is the intensity relationship between two points at distances r₁ and r₂ from a point source?

Accepted Answer

I₁/I₂ = (r₂/r₁)²

Answer

I₁/I₂ = r₂/r₁

Answer

I₁/I₂ = r₁/r₂

Answer

I₁/I₂ = (r₁/r₂)²

Question 3

When light travels from a medium with refractive index 1.5 into air (n=1), what is the critical angle?

Accepted Answer

41.8°

Answer

19.5°

Answer

48.2°

Answer

56.4°

Question 4

Which wave property allows sound to be heard around corners?

Accepted Answer

Diffraction

Answer

Reflection

Answer

Refraction

Answer

Polarisation

Question 5

If the amplitude of a wave is doubled, the intensity of the wave:

Accepted Answer

Quadruples

Answer

Doubles

Answer

Halves

Answer

Remains the same

Question 6

Electromagnetic waves are arranged in the electromagnetic spectrum in order of increasing frequency. Which of the following is the correct order?

Accepted Answer

Radio → Visible → X-ray → Gamma

Answer

Gamma → X-ray → Visible → Radio

Answer

Visible → Radio → X-ray → Gamma

Answer

X-ray → Gamma → Radio → Visible