NSAA Physics - Waves and Optics Flashcards

A wave has a frequency of 5 Hz and a wavelength of 4 m. What is its speed?

Answer: 20 m/s

Wave speed v = fλ = 5 × 4 = 20 m/s.

Which type of wave requires a medium to travel through?

Answer: Mechanical waves

Mechanical waves, such as sound, require a physical medium to propagate.

A light ray passes from air into glass and bends toward the normal. This is because in glass the light:

Answer: Travels slower

Light slows down when entering a denser medium, causing refraction toward the normal.

What is the period of a wave with frequency 50 Hz?

Answer: 0.02 s

Period T = 1/f = 1/50 = 0.02 s.

In the double-slit experiment, constructive interference occurs when the path difference between the two sources is:

Answer: Any multiple of λ

Constructive interference occurs when path difference = nλ (n = 0, 1, 2, ...), so waves arrive in phase.

A concave mirror has a focal length of 10 cm. An object is placed 30 cm in front of it. Where is the image formed?

Answer: 15 cm in front of the mirror

1/f = 1/v + 1/u → 1/10 = 1/v + 1/30 → 1/v = 3/30 - 1/30 = 2/30, so v = 15 cm in front.