Waves A levels

2 points on a progressive wave are 1/3 of a wavelength apart. The distance between the two points is 2cm. If the speed of the wave is 10 ms^-1 what is the frequency of the wave?

• 5Hz

• 20Hz

• 167Hz

• 1500Hz

Answer explanation

The frequency of the wave can be calculated using the formula: frequency = speed / wavelength. Since the distance between the two points is 2cm (1/3 of a wavelength), the wavelength is 6cm. Converting to meters, the wavelength is 0.06m. Therefore, frequency = 10 / 0.06 = 166.67Hz, which rounds to 167Hz.

A guitar string of length 80cm vibrates with a third harmonic frequency of 305Hz. What is the wavelength of the wave?

• 244cm

• 53.3cm

• 16.2cm

• 3.80cm

What is the approximate phase difference between the waves shown?

• 2π

• 3 π/2

• π

• π/2

The density of a nylon guitar string of diameter 1.0 x 10^-3m is 1.15 x 10³ kgm^-1. What is the mass per unit length, µ of the nylon string?

• 1.15 kg m^-1

• 1.15 x 10⁶ kg m^-1

• 3.6 x 10^-3 kg m^-1

• 9.0 x 10^-4 kg m^-1

The speed of light in a material is 1.7 x 108ms-1. What is the refractive index of the material?

• 0.57

• 1.43

• 1.76

• 2.31

A ray of light is incident on the internal boundary of a rectangular glass block in air.

Part of the light refracts out of the block at an angle of 30°.

Some of the remaining light reflects within the block to become incident on the right-hand

boundary. refractive index of glass = 1.48

• 20°

• 42°

• 48°

• 70°

A diffraction grating is illuminated normally.

The second-order maximum for light of wavelength 650 nm occurs at the same angle as the

third-order maximum for light of wavelength λ.

What is λ?

• 217 nm

• 325 nm

• 433nm

• 975nm

Stationary waves are set up on a rope of length 1.0 m fixed at both ends.

Which statement is not correct?

• The

  Second harmonic has a wavelength of 2.0 m.

• The midpoint of the rope is always stationary for

  even-numbered harmonics.

• A harmonic of wavelength 0.4 m can be set up on the rope.

• There are five nodes on the rope for the fifth harmonic.

Light of wavelength λ is incident normally on a diffraction grating for which adjacent lines are a

distance 3λ apart. What is the angle between the second order maximum and the

straight-through position?

• 9.6°

• 20

• 42

• There is no second order maximum